Undoing Nadine's jacket I dipped in pickle (7)
I believe the answer is:
nemesis
'undoing' is the definition.
(nemesis can mean someone's doom or undoing)
'nadine's jacket i dipped in pickle' is the wordplay.
'jacket' suggests removing the centre (the letters worn by the word as a 'jacket' are use).
'dipped in' indicates putting letters inside.
'pickle' becomes 'mess' (both can mean a difficult situation).
'nadine' with its centre taken out is 'ne'.
'i' put inside 'mess' is 'mesis'.
'ne'+'mesis'='NEMESIS'
(Other definitions for nemesis that I've seen before include "E'en miss (anag.)" , "Greek god of vengeance" , "Avenging deity" , "Something causing misery (or death) - Meissen (anag)" , "curse" .)