Protrude over centre of green fibrous plant (4)
I believe the answer is:
jute
'fibrous plant' is the definition.
(I've seen this before)
'protrude over centre of green' is the wordplay.
'protrude' becomes 'jut' (I've seen this before).
'over' is a charade indicator (letters next to each other).
'centre of' indicates the central letters.
The middle letter of 'green' is 'e'.
'jut'+'e'='JUTE'
(Other definitions for jute that I've seen before include "involved in sacking" , "Companion for Anglo-Saxon" , "Sacking plant; old tribesman" , "Old invader of England" , "Plant fibre used in making rope and sacks" .)