Female needs energy after party (3)
I believe the answer is:
doe
'female' is the definition.
(female deer)
'energy after party' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mc2).
'after' says to put letters next to each other.
'party' becomes 'do' (do can informally mean a party).
'e' put after 'do' is 'DOE'.
'needs' is the link.
(Other definitions for doe that I've seen before include "She's a deer" , "possible mate for Rudolph?" , "Female creature" , "partner for a buck" , "Feminine counterpart of stag" .)