Herb gathered for basic sauce (4)
I believe the answer is:
roux
'sauce' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for roux that I've seen before include "Mixture of fat and flour used for thickening sauces" , "Fat/flour sauce-mix" , "Sauce mixture" , "Mixture of flour and fat for cooking" , "sauce mix" .)