Master of what's invested in commercial ordering (4)
I believe the answer is:
lord
'master' is the definition.
(I know that master can be written as lord)
'what's invested in commercial ordering' is the wordplay.
'what's invested in' indicates the answer is hidden within the clue.
'LORD' is hidden in the letters of 'commercial ordering'.
'of' is the link.
(Other definitions for lord that I've seen before include "Proprietor of a manor?" , "Titled peer of the realm" , "Master, ruler or titled gent" , "aristocrat" , "Leader of the 'Six Hundred'" .)