Diplomacy here in France with a new strategist (9)
I believe the answer is:
tactician
'strategist' is the definition.
(I've seen this before)
'diplomacy here in france with a new' is the wordplay.
'diplomacy' becomes 'tact' (tact can mean diplomacy or sensitivity).
'here in france' becomes 'ici' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'tact'+'ici'+'a'+'n'='TACTICIAN'
(Other definitions for tactician that I've seen before include "One deploying forces in war" , "Military planner" , "General" , "Skilled planner" , "Chess player" .)