Catch partner briefly returning (6)
I believe the answer is:
entrap
'catch' is the definition.
(to entrap is to catch with a trap)
'partner briefly returning' is the wordplay.
'briefly' means to remove the last letter.
'returning' says the letters should be written in reverse.
'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 "Frame -- stitch up" , "Ensnare, catch" , "Capture" , "decoy" , "Deceive -- lead on" .)