Tried to set off for US city (7)
I believe the answer is:
detroit
'us city' is the definition.
(I've seen this before)
'tried to set off' is the wordplay.
'set off' indicates an anagram.
'tried'+'to'='triedto'
'triedto' anagrammed gives 'DETROIT'.
'for' is the link.
(Other definitions for detroit that I've seen before include "US motor city" , "US city associated with automobile production" , "Where cars are made" , "Origin of Motown" , "American city" .)