Making a comeback, dodgy weightlifter barely engrossed one egotist (9)
I believe the answer is:
narcissus
'one egotist' is the definition.
(I have seen 'Mythical egotist' mean 'narcissus' so perhaps 'egotist' could also mean 'narcissus')
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for narcissus that I've seen before include "He saw himself as most adorable" , "Beautiful youth; plant" , "In Greek myth, youth in love with his reflection" , "Greek youth who fell in love with his own reflection" , "Flower; Gk. youth in love with reflection" .)