Enthusiastic about entertaining good music (6)
I believe the answer is:
reggae
'music' is the definition.
(reggae is a kind of music)
'enthusiastic about entertaining good' is the wordplay.
'enthusiastic' becomes 'eager' (similar in meaning).
'about' says the letters should be written in reverse.
'entertaining' indicates putting letters inside (inviting in, as for dinner).
'good' becomes 'g' (abbreviation).
'eager' written backwards gives 'regae'.
'regae' enclosing 'g' is 'REGGAE'.
(Other definitions for reggae that I've seen before include "W. Indian music style" , "Bob Marley's music" , "Music style from Jamaica" , "Style of music originating in West Indies" , "Jamaican music style" .)