A loose woman goes west in US city (5)
I believe the answer is:
tulsa
'us city' is the definition.
(I've seen this before)
'a loose woman goes west' is the wordplay.
'loose woman' becomes 'slut' (synonyms).
'goes west' says the letters should be written backwards.
'a'+'slut'='aslut'
'aslut' back-to-front is 'TULSA'.
'in' acts as a link.
(Other definitions for tulsa that I've seen before include "An OK place" , "A lust for the Oklahoma oil city?" , "City in Oklahoma featured in a 60s song" , "Oklahoma city (only 24 hours away?)" , "Oklahoma river port" .)