Catch retired husband perhaps scratching rear (6)
I believe the answer is:
entrap
'catch' is the definition.
(to entrap is to catch with a trap)
'retired husband perhaps scratching rear' is the wordplay.
'retired' says the letters should be written backwards.
'husband perhaps' becomes 'partner' (husband is a type of partner).
'scratching rear' means to remove the last letter (the letter at the rear of the word is removed).
'partner' with its last letter taken away is 'partne'.
'partne' backwards is 'ENTRAP'.
(Other definitions for entrap that I've seen before include "Frame -- stitch up" , "decoy" , "Catch - frame" , "Trepan (anag.)" , "Parent (anag)" .)