Bush supporter left, decorated with medal? (7)
I believe the answer is:
bramble
'bush' is the definition.
(thesaurus)
'supporter left decorated with medal?' is the wordplay.
'supporter' becomes 'bra' (a bra gives support to breasts).
'left' becomes 'l' (common abbreviation).
'decorated with' means one lot of letters goes inside another (some letters decorate or go round others).
'medal?' becomes 'MBE' (Member of the British Empire medal).
'l' inserted into 'mbe' is 'mble'.
'bra'+'mble'='BRAMBLE'
(Other definitions for bramble that I've seen before include "Wild blackberry bush" , "Thorny bush" , "Source of fruit" , "Rough, prickly shrub" , "Briar" .)