The first territory to display diplomacy (4)
I believe the answer is:
tact
'diplomacy' is the definition.
(tact can mean diplomacy or sensitivity)
'the first territory' is the wordplay.
'the first' becomes 't' (ast letter of 'the').
'territory' becomes 'act' (I am not sure about this - if you are sure you should believe this answer much more).
't'+'act'='TACT'
'to display' is the link.
Can you help me to learn more?
(Other definitions for tact that I've seen before include "Diplomacy or discretion" , "Consideration in dealing with others" , "Fine perception" , "Sensitivity in dealings" , "Delicacy of feeling, skill in saying the right thing" .)