French writer having a lot of extra money to include murder victim (8)
I believe the answer is:
rabelais
'french writer' is the definition.
(I've seen this before)
'a lot of extra money to include murder victim' is the wordplay.
'a lot of' means to remove the last letter (a lot of the word but not all of it).
'extra money' becomes 'raise' (increase in pay).
'to include' indicates putting letters inside.
'murder victim' becomes 'abel' (biblical figure murdered by his brother Cain).
'raise' with its last letter removed is 'rais'.
'rais' placed around 'abel' is 'RABELAIS'.
'having' acts as a link.
(Other definitions for rabelais that I've seen before include "Racy writer" , "French writer" , "teller of stories" , "Sixteenth century French satirical author" , "16th-century French satirist, noted for earthy humour" .)