Token is returned by gutted Glaswegian gangster (6)
I believe the answer is:
signal
'token' is the definition.
'is returned by gutted glaswegian gangster' is the wordplay.
'returned' shows that the letters should be reversed in order.
'by' is a charade indicator (letters next to each other).
'gutted' suggests removing the centre (to gut something is to remove its insides).
'gangster' becomes 'al' (Al Capone).
'glaswegian' with its centre taken out is 'gn'.
'is' reversed gives 'si'.
'si'+'gn'+'al'='SIGNAL'
(Other definitions for signal that I've seen before include "Nonverbal action or gesture that encodes a message" , "Electrical transmission; striking in importance" , "Gesture with meaning" , "Noteworthy" , "Remarkable; gesture" .)