Robin's cowl? (4)
I believe the answer is:
hood
I believe this clue is a double definition.
'robin's' is the first definition.
(I've seen this in other clues)
'cowl?' is the second definition.
('hood' can be a synonym of 'cowl')
(Other definitions for hood that I've seen before include "Protective cover - violent criminal (slang)" , "Outlaw and gangster" , "Head covering of an American gangster" , "Bronx district" , "Head covering or American car bonnet" .)