To plagiarise writer is out of bounds (4)
I believe the answer is:
crib
'to plagiarise' is the definition.
(cribbing is a kind of plagiarizing)
'writer is out of bounds' is the wordplay.
'writer' becomes 'scribe' (scribe is a kind of writer).
'is out of bounds' says to take the centre (the bounds or edges of the word are removed).
The centre of 'scribe' is 'CRIB'.
(Other definitions for crib that I've seen before include "Cheat by copying - card game" , "Student's aid; bed" , "Cheat - Christmas scene" , "Manger; illegally copy" , "Pen" .)