He's masterly in control, ordinarily (4)
I believe the answer is:
lord
'he's masterly' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'in control ordinarily' is the wordplay.
'in' indicates a hidden word.
'LORD' is hidden within 'control ordinarily'.
Can you help me to learn more?
(Other definitions for lord that I've seen before include "Feudal superior" , "Dismayed expression; ruler" , "Member of the aristocracy" , "Proprietor of a manor?" , "aristocrat" .)