Satisfied about husband backsliding? Not us (4)
I believe the answer is:
them
'not us' is the definition.
(I've seen this before)
'satisfied about husband backsliding?' is the wordplay.
'satisfied' becomes 'met' ('meet' can be a synonym of 'satisfy').
'about' is an insertion indicator.
'husband' becomes 'h'.
'backsliding?' says the letters should be written in reverse.
'met' enclosing 'h' is 'meht'.
'meht' back-to-front is 'THEM'.
(Other definitions for them that I've seen before include "Others" , "(To/from) those people" , "Certainly not us, the other lot" , "Let -- eat cake" , "... in another case, they" .)