It means one's refusing in code perhaps (2,4)
I believe the answer is:
no dice
'it means one's refusing' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'in code perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'in'+'code'='incode'
'incode' with letters rearranged gives 'NO DICE'.
Can you help me to learn more?
(Other definitions for no dice that I've seen before include "Certainly not" , "Not a chance of co-operation" , "Emphatic refusal" , "indicates lack of success" , "Refusal (to play)" .)