Growing area one with a shrub (8)
I believe the answer is:
gardenia
'shrub' is the definition.
(gardenia is a kind of shrub)
'growing area one with a' is the wordplay.
'growing area' becomes 'garden' (I've seen this before).
'one' becomes 'I' (Roman numeral).
'with' is a charade indicator (letters next to each other).
'garden'+'i'+'a'='GARDENIA'
(Other definitions for gardenia that I've seen before include "Drainage for shrub with white or yellow flowers" , "Shrub such as the Cape jasmine" , "Fragrant tree or shrub" , "Fragrant shrub, red again (anag.)" , "Evergreen" .)