One-time recluse to return, revealing himself (7)
I believe the answer is:
eremite
'himself' is the definition.
I can't judge whether this definition defines the answer.
'one-time recluse to return revealing' is the wordplay.
'revealing' says the answer is hidden in the clue.
'to return' shows that the letters should be reversed in order.
'etimere' is hidden within 'one time recluse'.
'etimere' in reverse letter order is 'EREMITE'.
Can you help me to learn more?
(Other definitions for eremite that I've seen before include "Christian living in severe circumstances" , "ascetic" , "Religious person" , "Solitary" , "Christian hermit or recluse" .)