Get in touch with using conservative diplomacy (7)
I believe the answer is:
contact
'get in touch with' is the definition.
(I've seen this in another clue)
'conservative diplomacy' is the wordplay.
'conservative' becomes 'con' (abbreviation for Conservative).
'diplomacy' becomes 'tact' (tact can mean diplomacy or sensitivity).
'con'+'tact'='CONTACT'
'using' is the link.
(Other definitions for contact that I've seen before include "Close interaction" , "Connection" , "Juxtaposition" , "Useful acquaintance" , "Communication" .)