Digest cheese at first feast (5)
I believe the answer is:
brief
'digest' is the definition.
(thesaurus)
'cheese at first feast' is the wordplay.
'cheese' becomes 'brie' (Brie is an example).
'at first' says to take the initial letters.
The initial letter of 'feast' is 'f'.
'brie'+'f'='BRIEF'
(Other definitions for brief that I've seen before include "Document stating the facts of a legal case" , "Succinct" , "Short or concise" , "Using few words" , "Fibre (anag.)" .)