Tenner spent on cheese ingredient (6)
I believe the answer is:
rennet
'cheese ingredient' is the definition.
(curdled milk used in cheese)
'tenner spent' is the wordplay.
'spent' indicates anagramming the letters.
'tenner' is an anagram of 'RENNET'.
'on' acts as a link.
(Other definitions for rennet that I've seen before include "Cheese-maker's substance" , "Curdler of milk" , "cheesy setter?" , "Milk curdling agent" , "what you need to make cheese" .)