Unenthusiastic man with western member (8)
I believe the answer is:
lukewarm
'unenthusiastic' is the definition.
(similar in meaning)
'man with western member' is the wordplay.
'man' becomes 'luke' ().
'with' says to put letters next to each other.
'western' becomes 'w'.
'member' becomes 'arm' (member can mean a limb).
'luke'+'w'+'arm'='LUKEWARM'
(Other definitions for lukewarm that I've seen before include "Rather cool" , "Little enthusiasm" , "Not very keen" , "Unenthusiastic" , "Indifferent" .)