One makes proposal cancelled by monarch twice (7)
I believe the answer is:
offerer
'one makes proposal' is the definition.
(someone making a proposal)
'cancelled by monarch twice' is the wordplay.
'cancelled' becomes 'off' (similar in meaning).
'by' says to put letters next to each other.
'monarch' becomes 'er' (abbreviation for Elizabeth Regina).
'twice' says to double the letters.
'er' doubled is 'erer'.
'off'+'erer'='OFFERER'
(Other definitions for offerer that I've seen before include "One presenting something for acceptance" , "I propose" , "One proposing, bidding or presenting" .)