Performs in parties full of energy (4)
I believe the answer is:
does
'performs' is the definition.
('do' can be a synonym of 'perform')
'parties full of energy' is the wordplay.
'parties' becomes 'dos' (do is a kind of party).
'full of' is an insertion indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'dos' placed around 'e' is 'DOES'.
'in' is the link.
(Other definitions for does that I've seen before include "Deer; performs" , "Executes - female deer" , "female woodlanders" , "Suffices" , "Carries out" .)