Dish, excessive starter of olives, gentleman served up (7)
I believe the answer is:
risotto
'dish' is the definition.
(risotto is a kind of dish)
'excessive starter of olives gentleman served up' is the wordplay.
'excessive' becomes 'OTT' (short for 'over the top').
'starter of' suggests taking the first letters.
'gentleman' becomes 'sir' (a man may be addressed as sir).
'served up' shows that the letters should be reversed in order (in a down clue, going upwards).
The first letter of 'olives' is 'o'.
'ott'+'o'+'sir'='ottosir'
'ottosir' back-to-front is 'RISOTTO'.
(Other definitions for risotto that I've seen before include "Italian dish of rice, meat and vegetables" , "Italian dish cooked with broth" , "Italian food" , "Perhaps Italian" , "You cook it in stock" .)