Furze (5)
I believe the answer is:
gorse
'furze' is the definition.
(synonyms)
This is all the clue.
(Other definitions for gorse that I've seen before include "I'm always blooming" , "Prickly heath shrub" , "Spiny yellow-flowered shrub" , "Welsh assembly" , "Prickly shrub, furze, whin" .)