Communication of formal agreement to get rid of Republican (7)
I believe the answer is:
contact
'communication' is the definition.
(contact is a kind of communication)
'formal agreement to get rid of republican' is the wordplay.
'formal agreement' becomes 'contract'.
'to get rid of' indicates named letters should be taken away.
'republican' becomes 'r' (abbreviation).
'contract' with 'r' taken out is 'CONTACT'.
'of' acts as a link.
(Other definitions for contact that I've seen before include "Get hold of" , "Communication" , "Useful acquaintance" , "Touching" , "Maybe page" .)