Bound to find energy in drink (4)
I believe the answer is:
leap
'bound' is the definition.
('leap' can be a synonym of 'bound')
'energy in drink' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mca).
'in' means one lot of letters goes inside another.
'drink' becomes 'lap' (lapping is a kind of drinking**).
'e' placed within 'lap' is 'LEAP'.
'to find' is the link.
(Other definitions for leap that I've seen before include "Spring suddenly" , "Jump a long way" , "Basket" , "Jump, spring" , "Abrupt change; spring" .)