Cupid, to the Greeks (4)
I believe the answer is:
eros
'cupid to the greeks' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eros that I've seen before include "Greek equivalent to Roman Cupid" , "Form of love" , "Asteroid - Greek god of love" , "I'm in a circus in London" , "Circus boy" .)