Heartless saying brings hurt (4)
I believe the answer is:
maim
'hurt' is the definition.
(I've seen this before)
'heartless saying' is the wordplay.
'heartless' means to remove the middle letters.
'saying' becomes 'maxim' (maxim is a kind of saying).
'maxim' with its middle taken out is 'MAIM'.
'brings' is the link.
(Other definitions for maim that I've seen before include "Injure or harm severely" , "Wound or injure, disable" , "Cripple, mutilate" , "Severely damage" , "seriously hurt!" .)