Satirist, a sir able to be funny (8)
I believe the answer is:
rabelais
'satirist' is the definition.
(I know that Rabelais is a satirist)
'a sir able to be funny' is the wordplay.
'to be funny' indicates anagramming the letters.
'a'+'sir'+'able'='asirable'
'asirable' anagrammed gives 'RABELAIS'.
(Other definitions for rabelais that I've seen before include "French writer" , "Francois ......., 16th century French satirist - sort of base liar" , "Sixteenth century French author of Gargantua and Pantagruel" , "Creator of Gargantua" , "bawdy writer" .)