Unbridled desire (4)
I believe the answer is:
lust
'unbridled desire' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lust that I've seen before include "Lecherousness" , "Strong sexual desire" , "One of the seven deadly sins" , "Passionate desire" , "Intense sexual desire, a deadly sin" .)