He loves to hurt (6)
I believe the answer is:
sadist
'he loves to hurt' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he' is the wordplay.
I cannot quite see how this works, but
'he' could be 'ad' and 'ad' is found within the answer.
The remaining letters 'sist' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sadist that I've seen before include "Cruel type" , "One delighting in inflicting pain" , "One enjoying hurting others" , "One who enjoys cruelty" , "Cruel person, takes pleasure in it" .)