It's true corporation employs old dogsbody (8)
I believe the answer is:
factotum
'dogsbody' is the definition.
(I've seen this before)
'it's true corporation employs old' is the wordplay.
'it's true' becomes 'fact' (I've seen this before).
'corporation' becomes 'tum' ('corporation' is a humorous term for stomach fat).
'employs' means one lot of letters goes inside another.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'fact'+'tum'='facttum'
'facttum' going around 'o' is 'FACTOTUM'.
(Other definitions for factotum that I've seen before include "Odd-job servant" , "Dogsbody" , "Person employed for all kinds of work" , "Someone employed for a variety of jobs" , "Man Friday" .)