Model prisoner leaves study (8)
I believe the answer is:
template
'model' is the definition.
(template is a kind of model)
'prisoner leaves study' is the wordplay.
'prisoner' becomes 'con' (abbreviation for 'convict').
'leaves' indicates named letters should be taken away.
'study' becomes 'contemplate' (synonyms).
'contemplate' with 'con' taken away is 'TEMPLATE'.
(Other definitions for template that I've seen before include "Model or standard for making comparisons" , "Something used as a pattern" , "original design" , "Pattern or mould" , "Shaped pattern" .)