The second-largest city in Oklahoma (5)
I believe the answer is:
tulsa
'the second-largest city in oklahoma' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tulsa that I've seen before include "Oklahoma city (only 24 hours away?)" , "Major oil centre" , "A lust for the Oklahoma oil city?" , "Twenty-four Hours from - (Gene Pitney)" , "Oklahoma river port" .)