Charlie, out of practice, is irascible (6)
I believe the answer is:
crusty
'irascible' is the definition.
(thesaurus)
'charlie out of practice' is the wordplay.
'charlie' becomes 'C' (phonetic alphabet).
'out of practice' becomes 'rusty' (synonyms).
'c'+'rusty'='CRUSTY'
'is' is the link.
(Other definitions for crusty that I've seen before include "Curtsy (anag.)" , "Sour and brusque, like outer part of bread" , "Having harsh manner like hard bread" , "Ill-humoured" , "Cross or harsh, like outer layer of loaf" .)