Making excuse, do cut off a sexual urge (5)
I believe the answer is:
alibi
'making excuse' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for alibi that I've seen before include "Excuse for not doing something" , "Excuse - plea of being elsewhere" , "Timely excuse" , "Excuse for failure" , "it may help you to get off" .)