Bound with energy during circuit (4)
I believe the answer is:
leap
'bound' is the definition.
('leap' can be a synonym of 'bound')
'energy during circuit' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mc2).
'during' means one lot of letters goes inside another.
'circuit' becomes 'lap' ('lap' can be a synonym of 'circuit').
'e' inserted into 'lap' is 'LEAP'.
'with' acts as a link.
(Other definitions for leap that I've seen before include "as 1984 was" , "Jump across" , "Jump a long way" , "identify extra day?" , "Sort of year" .)