It has a canopy of raised support (6)
I believe the answer is:
forest
'it has a canopy' is the definition.
(I've seen this in another clue)
'of raised support' is the wordplay.
'raised' says the letters should be written backwards (going up in a down clue).
'support' becomes 'rest' (e.g. a shoulder rest is a support for shoulder).
'of' back-to-front is 'fo'.
'fo'+'rest'='FOREST'
(Other definitions for forest that I've seen before include "See 15" , "that has branches everywhere" , "Large densely wooded area" , "green area" , "Thief (rhyming slang)" .)