Strange moves by Glasgow's top criminal (8)
I believe the answer is:
gangster
'criminal' is the definition.
(gangster is a kind of criminal)
'strange moves by glasgow's top' is the wordplay.
'moves' is an anagram indicator.
'by' is a charade indicator (letters next to each other).
'top' suggests taking the first letters.
The initial letter of 'glasgows' is 'g'.
'strange' with letters rearranged gives 'angster'.
'angster' put after 'g' is 'GANGSTER'.
(Other definitions for gangster that I've seen before include "Mobster" , "Hoodlum" , "One of the mob, like Al Capone" , "Organised criminal" , "Hood, desperado" .)