A way of calculating a protracted share-out! (4,8)
I believe the answer is:
long division
'a way of calculating a' is the definition.
I can't judge whether this definition defines the answer.
'protracted share-out' is the wordplay.
'protracted' becomes 'long-' (similar in meaning).
'share-out' becomes 'division' (I can't justify this - if you can you should give a lot more credence to this answer).
'long'+'division'='LONG DIVISION'
Can you help me to learn more?
(Other definitions for long division that I've seen before include "Dealing with large numbers" , "Mathematical calculation" , "result of vendetta?" , "tedious disagreement" , "Mathematical operation" .)