Starter of pastry that is — for this dish? (3)
I believe the answer is:
pie
'this dish?' is the definition.
(I've seen this before)
'starter of pastry that is' is the wordplay.
'starter of' says to take the initial letters.
'that is' becomes 'ie' (abbreviation for id est, 'that is' in Latin).
The initial letter of 'pastry' is 'p'.
'p'+'ie'='PIE'
'for' acts as a link.
(Other definitions for pie that I've seen before include "welcome luxury" , "steak might go in this" , "Food baked under pastry" , "Small, former coin of India" , "In the sky, it's a hopeless idea" .)