Proposal cancelled by the late British monarch (5)
I believe the answer is:
offer
'proposal' is the definition.
(an offer is a proposal or suggestion)
'cancelled by the late british monarch' is the wordplay.
I cannot really understand how this works, but
'cancelled' could be 'off' (similar in meaning) and 'off' is located in the answer.
'monarch' could be 'er' (abbreviation for Elizabeth Regina, British Queen) and 'er' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for offer that I've seen before include "Proposal; reduced price" , "Hold out, tender" , "Expression of willingness to pay or give" , "hand" , "Propose; make available" .)