Ornamental garden
I believe the answer is:
parterre
'ornamental garden' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for parterre that I've seen before include "Part of the main floor of a threatre" , "Seating on the main floor of a theatre" , "Formally patterned flower garden" , "Ornamental arrangement of flower beds and paths -- rarer pet (anag)" , "Flower bed or beds" .)