Order to declare what to do with rotten food (4,2,3)
I believe the answer is:
spit it out
'to do with rotten food' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'order to declare' is the wordplay.
'order to' becomes 'spitit' (I can't justify this - if you can you should give a lot more credence to this answer).
'declare' becomes 'out' (outing is a kind of declaring).
'spitit'+'out'='SPIT IT OUT'
'what' acts as a link.
Can you help me to learn more?
(Other definitions for spit it out that I've seen before include "Say what one has to say" , "Speak your mind" , "Come on, say it quickly - or expectorate" , "Come on, say what you think - expectorate" , "Come on, say what's on your mind - expectorate if you wish" .)