Ready to accept a simple drink (7)
I believe the answer is:
sherbet
'drink' is the definition.
(I've seen this before)
'ready to accept a simple' is the wordplay.
'ready to' becomes 'set' (synonyms).
'accept' means one lot of letters goes inside another.
'a simple' becomes 'herb' (I've seen this before).
'set' going around 'herb' is 'SHERBET'.
(Other definitions for sherbet that I've seen before include "Foreign beer" , "Sweet fizzy, fruity, drink" , "Sweet fizzy powder" , "Powder for making fizzy drink" , "Sweet effervescent powder" .)