To be a warlock would fascinate a fellow! (7)
I believe the answer is:
bewitch
'fascinate a fellow' is the definition.
'bewitch' can be an answer for 'fascinate' (synonyms). I'm unsure of the 'a fellow' bit.
'to be a warlock would' is the wordplay.
I cannot quite understand how this works, but
'be' is present in the answer.
The remaining letters 'witch' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for bewitch that I've seen before include "Cast a spell upon" , "add glamour" , "Fascinate - charm" , "Captivate" , "Put under a magic spell, or charm" .)