Nothing good kept in reserve (2,3)
I believe the answer is:
on ice
'kept in reserve' is the definition.
(something on ice has been postponed or reserved)
'nothing good' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'good' becomes 'nice' (similar in meaning).
'o'+'nice'='ON ICE'
(Other definitions for on ice that I've seen before include "Awaiting decision" , "Suspended; chilled" , "In abeyance" , "In poky alone" , "Kept chilled" .)