Cunning wife getting into scrap (6)
I believe the answer is:
shrewd
'cunning' is the definition.
(thesaurus)
'wife getting into scrap' is the wordplay.
'wife' becomes 'w'.
'getting into' indicates putting letters inside.
'scrap' becomes 'shred' (I've seen this before**).
'w' inserted inside 'shred' is 'SHREWD'.
(Other definitions for shrewd that I've seen before include "Canny and clever" , "Clever and calculating" , "Craftily astute" , "Penetrating" , "'Astute, savvy (6)'" .)