The bounds of fictorial imitation (5)
I believe the answer is:
limit
'the bounds' is the definition.
('limit' can be a synonym of 'bounds')
'of fictorial imitation' is the wordplay.
'of' indicates a hidden word.
'LIMIT' can be found hidden inside 'fictorial imitation'.
(Other definitions for limit that I've seen before include "Hem in" , "maximum number" , "control" , "Ceiling" , "Furthest bound" .)