Shrub (yellow) suffering when cut by half (5)
I believe the answer is:
orach
'shrub' is the definition.
(type of plant)
'yellow suffering when cut by half' is the wordplay.
'yellow' becomes 'or' (heraldic term).
'suffering' becomes 'aching' (to ache is to suffer pain).
'when cut by half' suggests halving the letters.
'aching' cut in half is 'ach'.
'or'+'ach'='ORACH'
(Other definitions for orach that I've seen before include "Vegetable" , "spinach" .)