Boss, overseer (6)
I believe the answer is:
gaffer
I believe this is a double definition.
'boss' is the first definition.
(I know that boss can be written as gaffer)
'overseer' is the second definition.
(thesaurus)
(Other definitions for gaffer that I've seen before include "Informally, a boss or foreman" , "blunderer" , "Superior" , "Boss, overseer" , "An old person" .)