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