Retired model is a source of revelations (7)
I believe the answer is:
exposer
'a source of revelations' is the definition.
(someone exposing someone else)
'retired model' is the wordplay.
'retired' becomes 'ex' (prefix meaning former or onetime).
'model' becomes 'poser' (synonyms).
'ex'+'poser'='EXPOSER'
'is' acts as a link.
(Other definitions for exposer that I've seen before include "one reveals" , "One who uncovers (something)" , "I'll reveal" , "striptease artist perhaps" , "One shedding light on" .)