Potato starter and starchy food's cost (5)
I believe the answer is:
price
'cost' is the definition.
(the cost or price of something)
'potato starter and starchy food's' is the wordplay.
'starter' indicates taking the first letters.
'and' means one lot of letters go next to another.
'starchy food' becomes 'rice' (I've seen this in another clue).
The initial letter of 'potato' is 'p'.
'p'+'rice'='PRICE'
(Other definitions for price that I've seen before include "Value - figure" , "Betting odds" , "Fanny?" , "Amount for which a thing is sold" , "Jordan?" .)