Lively musical about entertaining clubs (6)
I believe the answer is:
active
'lively' is the definition.
(similar in meaning)
'musical about entertaining clubs' is the wordplay.
'musical' becomes 'evita' (Andrew Lloyd Webber musical).
'about' is a reversal indicator.
'entertaining' is an insertion indicator.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'evita' back-to-front is 'ative'.
'ative' enclosing 'c' is 'ACTIVE'.
(Other definitions for active that I've seen before include "(Of mind) alert, lively" , "militant" , "Dynamic, functioning" , "Working; moving" , "Moving frequently" .)