Painter perhaps needing energy to become entertainer (7)
I believe the answer is:
artiste
'entertainer' is the definition.
(I know that artiste is a type of music interpreter)
'painter perhaps needing energy' is the wordplay.
'painter perhaps' becomes 'artist' (painter is a kind of artist).
'needing' means one lot of letters go next to another.
'energy' becomes 'e' (physics symbol as in E=mc2).
'artist'+'e'='ARTISTE'
'to become' acts as a link.
(Other definitions for artiste that I've seen before include "professional dancer?" , "Attires like entertainer" , "Professional performer" , "Person playing" , "Attires (anag.)" .)