Work over short speech of gratitude before getting to food (6)
I believe the answer is:
potato
'food' is the definition.
(potato is a kind of food)
'work over short speech of gratitude before getting to' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'over' says the letters should be written in reverse.
'short speech of gratitude' becomes 'ta' (informal way of saying 'thank you').
'before getting' says to put letters next to each other.
'op' written backwards gives 'po'.
'po'+'ta'+'to'='POTATO'
(Other definitions for potato that I've seen before include "King Edward, for example" , "French wine region" , "Spud (6)" , "Food item (with eyes?)" , "Would be difficult to deal with if hot" .)