Catch colleague, endlessly shown up (6)
I believe the answer is:
entrap
'catch' is the definition.
(entrapping is a kind of catching)
'colleague endlessly shown up' is the wordplay.
'colleague' becomes 'partner' (I've seen this before).
'endlessly' means to remove the last letter.
'shown up' says the letters should be written backwards.
'partner' with its final letter taken off is 'partne'.
'partne' written backwards gives 'ENTRAP'.
(Other definitions for entrap that I've seen before include "Snare, trick" , "Frame -- stitch up" , "Lure into wrongdoing in order to arrest" , "net" , "Something to do with gin" .)