Starchy food father is about to turn to (6)
I believe the answer is:
potato
'starchy food' is the definition.
(I've seen this in another clue)
'father is about to turn to' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'is about' indicates putting letters inside.
'turn' shows that the letters should be reversed in order.
'to' written backwards gives 'ot'.
'pa' enclosing 'ot' is 'pota'.
'pota'+'to'='POTATO'
(Other definitions for potato that I've seen before include "Starchy tuber" , "Food item (with eyes?)" , "Maris Piper?" , "The veg is too apt, oddly" , "Relative of nightshade" .)