Plant of the buttercup family (7)
I believe the answer is:
anemone
'plant of the buttercup family' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for anemone that I've seen before include "Name one strange flower" , "Buttercup-like flower or sea animal" , "Plant; sea creature" , "Plant with brightly coloured flowers - found also in sea" , "Flowering plant - mean one (anag)" .)