Cereal in barley recently sent up (3)
I believe the answer is:
rye
'cereal' is the definition.
(rye is a kind of cereal)
'in barley recently sent up' is the wordplay.
'in' says the answer is hidden in the clue.
'sent up' shows that the letters should be reversed in order.
'eyr' is hidden within 'barley recently'.
'eyr' back-to-front is 'RYE'.
(Other definitions for rye that I've seen before include "Type of whisky" , "J D Salinger novel 'The Catcher in the ...'" , "Whisky; Sussex town" , "Grass - whiskey" , "American whisky" .)