Revolutionary bloke pens circular, writing in prison to radical linguist? (4,7)

'linguist?' is the definition.
(I know that Noam Chomsky is a linguist)

'revolutionary bloke pens circular writing in prison to radical' is the wordplay.
I cannot quite understand how this works, but
'circular' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
'writing' could be 'ms' (abbreviation for manuscript) and 'ms' is found in the answer.
'prison' could be 'choky' (choky is a kind of prison) and 'choky' is found within the remaining letters.
The remaining letters 'nam' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?