Monitor possibly not needing large chamois (5)
I believe the answer is:
izard
'chamois' is the definition.
(I've seen this before)
'monitor possibly not needing large' is the wordplay.
'monitor possibly' becomes 'lizard' (monitor is a kind of lizard).
'not needing' suggests deleting specific letters.
'large' becomes 'l'.
'lizard' with 'l' taken away is 'IZARD'.
(Other definitions for izard that I've seen before include "Chamois in the Pyrenees" , "Pyrenean creature" , "Antelope" .)