Betting it has energy and ill will (5)
I believe the answer is:
spite
'ill will' is the definition.
(I've seen this in another clue)
'betting it has energy' is the wordplay.
'betting' becomes 'sp'.
'has' means one lot of letters go next to another.
'energy' becomes 'e' (physics symbol as in E=mc2).
'sp'+'it'+'e'='SPITE'
'and' acts as a link.
(Other definitions for spite that I've seen before include "Venom" , "Hatred" , "Desire to hurt or annoy" , "animosity" , "Bitchiness or malice" .)