Drainage somehow needed for plant (8)
I believe the answer is:
gardenia
'plant' is the definition.
The answer is an example.
'drainage somehow needed' is the wordplay.
'somehow needed' indicates anagramming the letters.
'drainage' with letters rearranged gives 'GARDENIA'.
'for' acts as a link.
(Other definitions for gardenia that I've seen before include "Drainage (anag) -- plant" , "Waxlike flower" , "Shrub such as the Cape jasmine" , "Evergreen" , "Shrub with fragrant flowers - in Grade A (anag)" .)