Mahler played in part of Manhattan (6)
I believe the answer is:
harlem
'part of manhattan' is the definition.
('Harlem' is part of 'manhattan')
'mahler played' is the wordplay.
'played' is an anagram indicator.
'mahler' with letters rearranged gives 'HARLEM'.
'in' acts as a link.
(Other definitions for harlem that I've seen before include "some of the Big Apple" , "District of New York" , "Father (French)" , "NY community" , "Part of New York City" .)