Cook, with endlessly wealthy fool in charge (9)
I believe the answer is:
fricassee
'cook' is the definition.
(fricasseeing is a kind of cooking)
'endlessly wealthy fool in charge' is the wordplay.
'endlessly' means to remove the last letter.
'wealthy' becomes 'rich' (similar in meaning).
'fool' becomes 'ass' (both can mean a stupid person).
'in' indicates putting letters inside.
'charge' becomes 'fee' (fee is a kind of charge).
'rich' with its final letter removed is 'ric'.
'ric'+'ass'='ricass'
'ricass' placed inside 'fee' is 'FRICASSEE'.
'with' acts as a link.
(Other definitions for fricassee that I've seen before include "food" , "Safer ices (anag) - stew" , "Meat/veg stew, white sauce" , "Stew of meat in thick white sauce" , "Dish of fried meat in thick sauce" .)