Director with hard heart before disagreement (5)
I believe the answer is:
arrow
'director' is the definition.
(something that directs e.g. on a sign)
'hard heart before disagreement' is the wordplay.
'heart' says to take the centre.
'before' says to put letters next to each other.
'disagreement' becomes 'row' (row is a kind of disagreement).
The central letters of 'hard' are 'ar'.
'ar'+'row'='ARROW'
'with' is the link.
(Other definitions for arrow that I've seen before include "Archery projectile" , "Missile with a point" , "Missile for bowman" , "broadly distinguishing old convict" , "what may have killed Harold?" .)