Lower, large hood (4)
I believe the answer is:
cowl
'hood' is the definition.
('cowl' can be a synonym of 'hood')
'lower large' is the wordplay.
'lower' becomes 'cow'.
'large' becomes 'l'.
'cow'+'l'='COWL'
(Other definitions for cowl that I've seen before include "form of protection?" , "Hood-shaped covering" , "Cover for monk or chimney" , "Hood for monk or chimney" , "Monk's hood or chimney covering" .)