Kitchen ingredient a pointer to grub (9)
I believe the answer is:
arrowroot
'kitchen ingredient' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'a pointer to grub' is the wordplay.
'a pointer' becomes 'arrow' ('arrow' can be a synonym of 'pointer').
'to grub' becomes 'root' (I've seen this before).
'arrow'+'root'='ARROWROOT'
Can you help me to learn more?
(Other definitions for arrowroot that I've seen before include "Nutritious starch from a West Indian plant" , "Medicinal plant" , "Starch used for thickening sauces etc" , "Carib foodstuff" , "that thickens" .)