Condiment Bill allowed, Sarah briefly admitted (5,4)
I believe the answer is:
table salt
'condiment' is the definition.
(I've seen this before)
'bill allowed sarah briefly admitted' is the wordplay.
'bill' becomes 'tab' (tab is a kind of bill**).
'allowed' becomes 'let' (I've seen this before).
'sarah' becomes 'sall' (Sally is a common pet form of Sarah).
'briefly' means to remove the last letter.
'admitted' indicates putting letters inside.
'sall' with its last letter removed is 'sal'.
'let' placed around 'sal' is 'lesalt'.
'tab'+'lesalt'='TABLE SALT'
(Other definitions for table salt that I've seen before include "It adds zest to meals" , "Seasoning for meal" , "food additive" , "contents of cellar" , "item on board" .)