Chief, principal (4)
I believe the answer is:
head
I believe this clue is a double definition.
'chief' is the first definition.
(synonyms)
'principal' is the second definition.
(synonyms)
(Other definitions for head that I've seen before include "Be in charge of; (come to) crisis" , "See 25" , "Leader; water pressure" , "Lead - school principal" , "Chief; go first" .)