Disgruntled old dons chef feeds crackers (7,3)
I believe the answer is:
cheesed off
'disgruntled' is the definition.
(I've seen this before)
'old dons chef feeds crackers' is the wordplay.
'old' becomes 'o' (abbreviation).
'dons' is an insertion indicator (don can mean to wear or be covered in).
'crackers' is an anagram indicator (informal term for mad).
'chef'+'feeds'='cheffeeds'
'cheffeeds' with letters rearranged gives 'cheesedff'.
'o' put into 'cheesedff' is 'CHEESED OFF'.
(Other definitions for cheesed off that I've seen before include "Fed up, disgruntled" , "frustrated" , "Unhappy" , "Cross" , "Not at all happy" .)