Obscure park keeper mentioned plant (9)
I believe the answer is:
hydrangea
'plant' is the definition.
The answer is an example.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for hydrangea that I've seen before include "Shrub of the saxifrage family -- angry head (anag)" , "Shrubby plant with showy flowers" , "Plant's" , "Shrub - garden hay (anag)" , "Common garden plant" .)