Right to stop an ancient fellow (6)
I believe the answer is:
arnold
'fellow' is the definition.
Both the answer and definition are singular nouns.
Maybe there's a link between them I don't understand?
'right to stop an ancient' is the wordplay.
'right' becomes 'r' (common abbreviation).
'to stop' means one lot of letters goes inside another.
'ancient' becomes 'old' (similar in meaning).
'r' going inside 'an' is 'arn'.
'arn'+'old'='ARNOLD'
Can you help me to learn more?
(Other definitions for arnold that I've seen before include "Sir Malcolm -, English composer" , "Headmaster, poet or composer" , "-- Wesker, playwright" , "Matthew --, English poet" , "Sir Malcolm -, composer (Bridge over the River Kwai)" .)