Reveal former model (6)
I believe the answer is:
expose
'reveal' is the definition.
(exposing is a kind of revealing)
'former model' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'model' becomes 'pose' (model can mean to pose).
'ex'+'pose'='EXPOSE'
(Other definitions for expose that I've seen before include "Reveal or unmask" , "Make visible or apparent" , "Uncover or unmask" , "brings out crime" , "Show up" .)