Artists turned up to eat fish (7)
I believe the answer is:
sardine
'fish' is the definition.
(sardine is a kind of fish)
'artists turned up to eat' is the wordplay.
'artists' becomes 'ras' (Royal Academicians abbreviation).
'turned up' shows that the letters should be reversed in order.
'to eat' becomes 'dine' (dining is a kind of eating).
'ras' in reverse letter order is 'sar'.
'sar'+'dine'='SARDINE'
(Other definitions for sardine that I've seen before include "Young pilchard" , "Small pilchard" , "Small fish, usually canned" , "Fish in tin?" , "A diner's small fish" .)