Herbs: bases for sauces, say (4)
I believe the answer is:
rues
'herbs' is the definition.
(rue is a kind of herb)
'bases for sauces say' is the wordplay.
'bases for sauces' becomes 'roux'.
'say' shows a homophone (sound like).
'roux' sounds like 'RUES'.
(Other definitions for rues that I've seen before include "Regrets, to be sure" , "Bemoans" , "Is sorry for - plants" .)