Captain (6)
'captain' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for leader that I've seen before include "Principal player in an orchestra" , "Opinion piece; boss" , "Front-runner or head of group" , "Chief or front man" , "One in command" .)
'captain' is the definition.
(I know that captain can be written as skipper)
This is the entire clue.
(Other definitions for skipper that I've seen before include "Ship's captain (colloq.)" , "one that's put over the side" , "Chap aboard trawler" , "sleep in outhouse" , "girl with rope?" .)