I fell off seat having fish (4)
I believe the answer is:
char
'fish' is the definition.
(char is a kind of fish)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for char that I've seen before include "Fish < tea" , "Singe, scorch" , "'Mrs Mopp'" , "(Work as a) cleaner" , "Tea - cleaning lady" .)