Emperor having no time to eat fish (7)
I believe the answer is:
sardine
'fish' is the definition.
(I know that sardine is a type of fish)
'emperor having no time to eat' is the wordplay.
'emperor' becomes 'tsar' (I've seen this before).
'having no' indicates named letters should be taken away.
'time' becomes 't' (abbreviation).
'to eat' becomes 'dine' (to dine is to eat a meal).
'tsar' with 't' removed is 'sar'.
'sar'+'dine'='SARDINE'
(Other definitions for sardine that I've seen before include "Small pilchard" , "FRENCH FISH" , "Small fish, usually canned" , "Rinsed a (anag) - fish" , "Stonefish OR? Stone" .)