Man, maybe, in his leathers (4)
I believe the answer is:
isle
'man maybe' is the definition.
(Isle of Man)
'in his leathers' is the wordplay.
'in' indicates a hidden word.
'ISLE' can be found hidden inside 'his leathers'.
(Other definitions for isle that I've seen before include "Detached territory" , "Sea-girt area" , "Could be Man" , "---- of Dogs, Thames peninsula" , "one has water all round" .)