Charlie plays unusual love ballad (7)
I believe the answer is:
calypso
'ballad' is the definition.
(thesaurus)
'charlie plays unusual love' is the wordplay.
'charlie' becomes 'c' (phonetic alphabet: alpha, bravo, charlie etc.).
'unusual' is an anagram indicator.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'plays' with letters rearranged gives 'alyps'.
'c'+'alyps'+'o'='CALYPSO'
(Other definitions for calypso that I've seen before include "sarcastic air" , "W. Indian ballad" , "West Indian music style" , "ad-libbed, topical ballad" , "Ballad - dance - orchid - sea nymph - moon of Saturn" .)