Fists cutting head after prisoner's lies (8)

I believe the answer is:

consists

'lies' is the definition.
('consist' can be a synonym of 'lie')

'fists cutting head after prisoner's' is the wordplay.
'cutting head' means to remove the first letter.
'after' says to put letters next to each other.
'prisoner's' becomes 'cons' (abbreviation for 'convict').
'fists' with its first letter taken off is 'ists'.
'ists' put after 'cons' is 'CONSISTS'.

(Another definition for consists that I've seen is " Comprises".)

I've seen this clue in The Telegraph.

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