Enforce the writer’s model (6)
I believe the answer is:
impose
'enforce' is the definition.
(I know that enforce can be written as impose)
'writer's model' is the wordplay.
'writer's' becomes 'I'm' ('I am' referring to the writer of the clue).
'model' becomes 'pose' (model can mean to pose).
'im'+'pose'='IMPOSE'
'the' is the link.
(Other definitions for impose that I've seen before include "As task, set" , "Intrude or inflict upon" , "Force upon or intrude" , "Lay as burden, onus" , "Put burden or tax on" .)