Small, hard, and chewy collection of plants (9)
I believe the answer is:
shrubbery
'collection of plants' is the definition.
(I've seen this before)
'small hard and chewy' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'and' is a charade indicator (letters next to each other).
'chewy' becomes 'rubbery' (as in rubbery food).
's'+'h'+'rubbery'='SHRUBBERY'
(Other definitions for shrubbery that I've seen before include "collection of plants" , "Area of small bushes" , "Bushy garden area" , "That might go in bed" , "Area where bushes are planted" .)