Former partner modelled naked (7)
I believe the answer is:
exposed
'naked' is the definition.
(I've seen this before)
'former partner modelled' is the wordplay.
'former partner' becomes 'ex' (an ex-partner).
'modelled' becomes 'posed' (model and pose are synonyms).
'ex'+'posed'='EXPOSED'
(Other definitions for exposed that I've seen before include "naked" , "Laid bare" , "Without protection" , "Showed up" , "Brought to light" .)