Editor worked first on Tamla Motown (7)
I believe the answer is:
detroit
'motown' is the definition.
(I've seen this in another clue)
'editor worked first on tamla' is the wordplay.
'worked' is an anagram indicator.
'first on' says to take the initial letters.
The first letter of 'tamla' is 't'.
'editor' is an anagram of 'detroi'.
'detroi'+'t'='DETROIT'
(Other definitions for detroit that I've seen before include "Major Great Lake port" , "Michigan car city" , "City also called Mo'town in USA" , "Where cars are made" , "Motown, Mich." .)