The writer returned Sir Henry, to simmer some food (5,4)
I believe the answer is:
irish stew
'some food' is the definition.
(Irish stew is an example)
'the writer returned sir henry to simmer' is the wordplay.
'the writer' becomes 'I' (the person who is writing these clues).
'returned' says the letters should be written backwards.
'henry' becomes 'H' (symbol for the unit of electrical inductance).
'to simmer' becomes 'stew' (I've seen this before).
'sir' reversed gives 'ris'.
'i'+'ris'+'h'+'stew'='IRISH STEW'
(Other definitions for irish stew that I've seen before include "Dish of meat, onions, potatoes etc" , "Mutton/onion/potato dish" , "casserole" , "National dish, boiled mutton, spuds and onions" , "Local dish of meat, potatoes and onions" .)