Some Parisian with big belly, a tyrant (6)
I believe the answer is:
despot
'a tyrant' is the definition.
(I know that tyrant can be written as despot)
'some parisian with big belly' is the wordplay.
'some parisian' becomes 'des' ('some' in French).
'with' says to put letters next to each other.
'big belly' becomes 'pot' (as in a pot belly).
'des'+'pot'='DESPOT'
(Other definitions for despot that I've seen before include "Possibly 4 [CZAR]" , "Cruel and oppressive ruler" , "Autocrat" , "Tyrant, oppressor" , "A ruler with unrestricted power" .)