Shrewd chief (4)
I believe the answer is:
arch
This clue is a double definition.
'shrewd' is the first definition.
(thesaurus)
'chief' is the second definition.
('arch' can be a synonym of 'chief')
(Other definitions for arch that I've seen before include "Chief - supporter - cunning" , "Shrewd; bridge" , "Way though - on foot!" , "Vaulted opening" , "which may fall and inconvenience walkers" .)