Chief officer maintains authority over a worker (10)
I believe the answer is:
commandant
'chief officer maintains' is the definition.
I can't tell whether this definition defines the answer.
'authority over a worker' is the wordplay.
'authority' becomes 'command' (command is a kind of authority).
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'a worker' becomes 'ant' (worker is a type of ant).
'command'+'ant'='COMMANDANT'
Can you help me to learn more?
(Other definitions for commandant that I've seen before include "one who takes charge" , "Officer in charge of a place or group of troops" , "Military officer in charge of a place" .)