Time left in USA for oil centre (5)
I believe the answer is:
tulsa
'oil centre' is the definition.
(I've seen this before)
'time left in usa' is the wordplay.
'time' becomes 't' (abbreviation).
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'l' inserted inside 'usa' is 'ulsa'.
't'+'ulsa'='TULSA'
'for' acts as a link.
(Other definitions for tulsa that I've seen before include "Oklahoman city" , "Twenty-four Hours from - (Gene Pitney)" , "A lust for the Oklahoma oil city?" , "City in Oklahoma featured in a 60s song" , "Where in the States" .)