Clean vegetation (5)
I believe the answer is:
scrub
This clue is a double definition.
'clean' is the first definition.
(scrub can mean to clean)
'vegetation' is the second definition.
(I know that scrub is a type of vegetation)
(Other definitions for scrub that I've seen before include "Area of dense stunted vegetation" , "Brush dirt off - delete - stunted vegetation" , "Axe" , "Do away with" , "Clean thoroughly - cancel" .)