Labour is not trying to thwart Brexit, shadow Welsh Secretary Christina Rees has said.
She defended Labour's decision to support calls to delay Article 50 ahead of a Commons vote on Tuesday.
The MP for Neath said the decision comes because the party is seeking a "pause" for a good deal, not to stop the process entirely.
It comes after a former Welsh minister said the Labour leader Jeremy Corbyn "doesn't have a clue" on Brexit.
MPs are in the process of voting on a series of amendments on alternatives to Theresa May's Brexit plan.
Labour supported an amendment by Yvette Cooper to create a bill enabling the UK's departure from the EU to be delayed by up to nine months if the prime minister does not have a plan agreed in Parliament by the end of February.
Labour said had backed the amendment because the bill it would create could "give MPs a temporary window to agree a deal that can bring the country together".
The amendment was defeated - 321 votes to 298.
But Mr Corbyn told the Commons Labour wanted a shorter window of three months to allow time for a deal to be finalised.
Ms Rees denied Labour was risking Brexit not happening at all by backing the motion.
"It's not to delay Brexit, it's to pause and give time to get a good deal," she told BBC Wales Live.
"I say to to Leave voters there will be Brexit. We're committed to the result of the referendum.
"But we want a good deal. We don't want to crash out with no deal."
AMs in the National Assembly for Wales will have their own vote on a proposed way forward on Wednesday.
The wording of the motion tabled by Welsh ministers will depend on what happens in Westminster on Tuesday night, when MPs are due to vote on amendments that could shape the next stage of negotiations with the EU.
But even if ministers do not propose a second referendum, Plaid Cymru is likely to table an amendment in the Senedd that gives AMs an opportunity to call for it.
Meanwhile, in a blog, former local government secretary Alun Davies said the "confusion from Labour's Westminster front bench has made me wince in pain".
The Labour AM backs a further referendum and was left out of Mark Drakeford's new Welsh cabinet.
"Drift" in Labour's position was shown by confusion over a Commons vote on the immigration bill on Monday, said Mr Davies.
He said that "simply pointing out the chaos caused by Theresa May's incompetence is not a policy".
"I have worried for some time that the UK party leadership doesn't have a clue what to do or where to go on Brexit," he said.
"And unhappily over the last few weeks they've proved it. And on the biggest issue of our time. That's really something."
He applauded the Welsh Government for explaining what it was doing to prepare for a no-deal Brexit in a series of statements last Tuesday.
At that time, Mr Drakeford said Westminster should be allowed another week to solve the deadlock before a second referendum becomes necessary.
Asked whether that deadline would pass on Tuesday night following a series of further votes in the Commons, Welsh Government Brexit Minister Jeremy Miles said they would "keep that under review".
The Welsh Government wants the UK's exit from the EU to be delayed beyond March 29, and for Theresa May to negotiate a softer Brexit that gives Britain full access to the single market and keeps it in the customs union.