Hearty complaint from gang in Arbroath (6)
I believe the answer is:
angina
'hearty complaint' is the definition.
(complaint of the heart)
'from gang in arbroath' is the wordplay.
'from' indicates the answer is hidden within the clue.
'ANGINA' is hidden within 'gang in arbroath'.
(Other definitions for angina that I've seen before include "heartfelt complaint?" , "Sharp chest pain caused by heart disease" , "Painful heart condition" , "Cardiac complaint" , "Painful heart complaint." .)