Diplomacy changed direction, we hear (4)
I believe the answer is:
tact
'diplomacy' is the definition.
(tact can mean diplomacy or sensitivity)
'changed direction we hear' is the wordplay.
'changed direction' becomes 'tacked' (tack can mean to change direction when sailing).
'we hear' shows a homophone (sound like).
'tacked' sounds like 'TACT'.
(Other definitions for tact that I've seen before include "Sensitivity (in dealing with others)" , "measure of diplomacy?" , "Diplomatic skill" , "Consideration in dealing with others" , "Sensitivity, diplomacy" .)