Harpy's head covered by artist with a plant (6)
I believe the answer is:
dahlia
'plant' is the definition.
The answer is an example.
'harpy's head covered by artist with a' is the wordplay.
'head' suggests taking the first letters.
'covered by' indicates putting letters inside.
'artist' becomes 'dali' (I've seen this before).
'with' says to put letters next to each other.
The first letter of 'harpy' is 'h'.
'h' going inside 'dali' is 'dahli'.
'dahli'+'a'='DAHLIA'
(Other definitions for dahlia that I've seen before include "Flower genus" , "Had Lia this peculiar flower?" , "Flower from tuber" , "Garden plant with large brightly-coloured flowers" , "Ali had (anag) - showy flower" .)