Spiny yellow-flowered shrub (5)
I believe the answer is:
gorse
'spiny yellow-flowered shrub' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for gorse that I've seen before include "Moorland shrub" , "Spiny yellow-flowered shrub" , "furs, say" , "Spiny heathland shrub" , "Welsh assembly" .)