Love god angry when rejected (4)
I believe the answer is:
eros
'love god' is the definition.
(I've seen this before)
'angry when rejected' is the wordplay.
'angry' becomes 'sore' (similar in meaning).
'when rejected' says the letters should be written in reverse.
'sore' reversed gives 'EROS'.
(Other definitions for eros that I've seen before include "Greek equivalent to Roman Cupid" , "London landmark" , "Circus boy" , "Cupid's Greek alternative" , "Cupid, to the Greeks" .)