Uncertain? Undo bit anyway (2,5)
I believe the answer is:
in doubt
'uncertain?' is the definition.
(I've seen this before)
'undo bit anyway' is the wordplay.
'anyway' indicates an anagram.
'undo'+'bit'='undobit'
'undobit' is an anagram of 'IN DOUBT'.
(Other definitions for in doubt that I've seen before include "Not sure" , "Unresolved" , "Open to question" , "Undecided" , "Uncertain" .)