Beguile retiring colleague no end (6)
I believe the answer is:
entrap
'beguile' is the definition.
(I've seen this before)
'retiring colleague no end' is the wordplay.
'retiring' shows that the letters should be reversed in order.
'colleague' becomes 'partner' (I've seen this before).
'no end' means to remove the last letter.
'partner' with its last letter taken away is 'partne'.
'partne' backwards is 'ENTRAP'.
(Other definitions for entrap that I've seen before include "Capture" , "Catch like parent" , "Take" , "Set up" , "Deceive -- lead on" .)