Deceive husband? What an idiot I am! (3)
I believe the answer is:
doh
'what an idiot i am' is the definition.
(exclamation expressing recognition of stupidity)
'deceive husband?' is the wordplay.
'deceive' becomes 'do' (do can mean to trick or deceive).
'husband?' becomes 'h' (abbreviation).
'do'+'h'='DOH'
(Other definitions for doh that I've seen before include "First note of tonic sol-fa scale" , "Silly me!" , "Tonic (mus.)" , "for 7 [HOMER] of course!" , "It begins the tonic solfa" .)