Diplomat's skill (4)
I believe the answer is:
tact
'diplomat's skill' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tact that I've seen before include "Sensitivity (in dealing with others)" , "Understanding" , "measure of diplomacy?" , "Consideration in dealing with others" , "Delicacy of feeling, skill in saying the right thing" .)