Sweet account of feelings kept hidden. (6)
I believe the answer is:
toffee
'sweet' is the definition.
(toffee is a kind of sweet)
'account of feelings kept hidden' is the wordplay.
'hidden' indicates a hidden word.
'TOFFEE' is hidden in the letters of 'account of feelings kept'.
(Other definitions for toffee that I've seen before include "Sweet made with heated butter and sugar" , "Chewy confection" , "Caramel" , "Type of sweet" , "Chewy confectionery" .)