Diplomacy leads to improved communications strategy (6)
I believe the answer is:
tactic
'strategy' is the definition.
(I've seen this in another clue)
'diplomacy leads to improved communications' is the wordplay.
'diplomacy' becomes 'tact' (tact can mean diplomacy or sensitivity).
'leads to' suggests taking the first letters.
The first letters of 'improved communications' is 'ic'.
'tact'+'ic'='TACTIC'
(Other definitions for tactic that I've seen before include "Planned manoeuvre or skilful move" , "Ruse, strategy" , "Device" , "Stratagem, procedure" , "A manoeuvre or planned action" .)