Pudding starch (4)
I believe the answer is:
sago
'pudding starch' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sago that I've seen before include "Cereal, used in pudding" , "Starchy cereal used in puddings" , "Starchy foodstuff" , "Powdery starch from a palm" , "Starchy grain used in desserts" .)