Weasel out (6)
I believe the answer is:
renege
'weasel out' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for renege that I've seen before include "Fail to follow suit at cards" , "Fail to keep promise, or revoke in cards" , "In card games, revoke" , "Fail to follow suit or fulfil a promise" , "Fail to carry out a commitment" .)