Agency worker, former model (8)
I believe the answer is:
template
'model' is the definition.
(template is a kind of model)
'agency worker former' is the wordplay.
'agency worker' becomes 'temp'.
'former' becomes 'late'.
'temp'+'late'='TEMPLATE'
(Other definitions for template that I've seen before include "Shaped pattern" , "Prototype" , "Model or standard for making comparisons" , "Design model" , "Pattern, model" .)