Sleazy nightclub limiting Romeo's enthusiasm (5)
I believe the answer is:
drive
'enthusiasm' is the definition.
(thesaurus)
'sleazy nightclub limiting romeo's' is the wordplay.
'sleazy nightclub' becomes 'dive'.
'limiting' is an insertion indicator.
'romeo' becomes 'r' (phonetic alphabet: alpha, bravo, charlie etc.).
'dive' enclosing 'r' is 'DRIVE'.
(Other definitions for drive that I've seen before include "High motivation, ambition" , "Use Aston Martin, say" , "zip" , "Motor < car storage space" , "run saloon?" .)