Our mixture number ten is used for sauces (4)
I believe the answer is:
roux
'sauces' is the definition.
(I know that roux is a sauces)
'our mixture number ten' is the wordplay.
'mixture' is an anagram indicator.
'number ten' becomes 'x' (Roman numeral).
'our' is an anagram of 'rou'.
'rou'+'x'='ROUX'
'is used for' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for roux that I've seen before include "Butter and flour sauce combination" , "Fat and flour mixture, cooked and used to make sauces" , "Thickener for sauces" , "Mixture of butter and flour used for sauces" , "Sauce mixture" .)