Gentleman sent back German dish (7)
I believe the answer is:
risotto
'dish' is the definition.
(risotto is a kind of dish)
'gentleman sent back german' is the wordplay.
'gentleman' becomes 'sir' (I've seen this before).
'sent back' shows that the letters should be reversed in order.
'german' becomes 'otto' (I've seen this before).
'sir' written backwards gives 'ris'.
'ris'+'otto'='RISOTTO'
(Other definitions for risotto that I've seen before include "Italian course" , "Main course" , "Italian dish of rice, meat and vegetables" , "dishy thing!" , "You cook it in stock" .)