Enthusiastic female singer turned up (4)
I believe the answer is:
avid
'enthusiastic' is the definition.
(similar in meaning)
'female singer turned up' is the wordplay.
'female singer' becomes 'diva' (term for a famous opera singer).
'turned up' says the letters should be written backwards.
'diva' backwards is 'AVID'.
(Other definitions for avid that I've seen before include "Very keen, desirous" , "Greatly desirous" , "Keen, enthusiastic" , "Showing a very keen interest in something" , "hungry" .)