She's no serious revolutionary (7)

I believe the answer is:

mildred

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'she's' is the definition.
(I've seen this before)

'no serious revolutionary' is the wordplay.
'no serious' becomes 'mild' (I can't justify this - if you can you should believe this answer much more).
'revolutionary' becomes 'red' (red can informally mean communist).
'mild'+'red'='MILDRED'

Can you help me to learn more?

(Other definitions for mildred that I've seen before include "Girl" , "Woman" , "lady?" .)

I've seen this clue in the Evening Standard.

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