Madman trapping bird in raincoat (6)
I believe the answer is:
maniac
'madman' is the definition.
(I've seen this before)
'bird in raincoat' is the wordplay.
'bird' becomes 'ani' (ani is a kind of bird**).
'in' indicates putting letters inside.
'raincoat' becomes 'mac' (mac is a kind of raincoat).
'ani' put inside 'mac' is 'MANIAC'.
'trapping' is the link.
This may not be correct. It may be part of another bit of the clue.
(Other definitions for maniac that I've seen before include "Psychopath" , "Can aim (anag.)" , "Lunatic, madman" , "Obsessive enthusiast" , "Psycho" .)