Leading Republican is one no good revolutionary (8)
I believe the answer is:
uprising
'revolutionary' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'leading republican is one no good' is the wordplay.
'leading' becomes 'up' (up can mean winning a sports match).
'republican' becomes 'R' (abbreviation).
'one' becomes 'i' (Roman numeral).
'no good' becomes 'ng' (abbreviation).
'up'+'r'+'is'+'i'+'ng'='UPRISING'
Can you help me to learn more?
(Other definitions for uprising that I've seen before include "Mutiny" , "Open rebellion" , "Insurrection or revolt" , "Rebellion, revolt" , "A revolting action?" .)