Catch husband maybe nearly keeling over (6)
I believe the answer is:
entrap
'catch' is the definition.
(to entrap is to catch with a trap)
'husband maybe nearly keeling over' is the wordplay.
'husband maybe' becomes 'partner' (husband is a type of partner).
'nearly' means to remove the last letter.
'keeling over' says the letters should be written in reverse (in a down clue, words go up).
'partner' with its final letter taken off is 'partne'.
'partne' in reverse letter order is 'ENTRAP'.
(Other definitions for entrap that I've seen before include "Catch in a snare" , "Set up" , "Lure into wrongdoing in order to arrest" , "Snare, trick" , "Something to do with gin" .)