Old flame, rich model (7)
I believe the answer is:
example
'model' is the definition.
('example' can be a synonym of 'model')
'old flame rich' is the wordplay.
'old flame' becomes 'ex' (I've seen this in other clues).
'rich' becomes 'ample' ('ample' can be a synonym of 'rich').
'ex'+'ample'='EXAMPLE'
(Other definitions for example that I've seen before include "Thing characteristic of its kind" , "Punishment" , "Specimen, illustration" , "Model - instance" , "Thing illustrating a general rule" .)