Spouse not totally up to net (6)
I believe the answer is:
entrap
'to net' is the definition.
(I've seen this in another clue)
'spouse not totally up' is the wordplay.
'spouse' becomes 'partner' (synonyms).
'not totally' means to remove the last letter.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'partner' with its final letter taken away is 'partne'.
'partne' back-to-front is 'ENTRAP'.
(Other definitions for entrap that I've seen before include "Catch in a snare" , "Parent (anag)" , "Catch - frame" , "Lure into wrongdoing in order to arrest" , "Ensnare, catch" .)