Particular corporation after old odd-jobber (8)
I believe the answer is:
factotum
'particular' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'corporation after old odd-jobber' is the wordplay.
'corporation' becomes 'tum' ('corporation' can humorously mean belly fat).
'after' means one lot of letters go next to another.
'old odd jobber' becomes 'facto' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'tum' after 'facto' is 'FACTOTUM'.
Can you help me to learn more?
(Other definitions for factotum that I've seen before include "Handyman" , "Man Friday" , "One employed to do various jobs" , "Employee who does all kinds of work (8)" , "General servant" .)