Hoist flag (4)
I believe the answer is:
jack
I believe this is a double definition.
'hoist' is the first definition.
(thesaurus)
'flag' is the second definition.
(jack is a kind of flag)
(Other definitions for jack that I've seen before include "Raising device, socket" , "Face card" , "Boy - lifting device" , "See 5 Down" , "PANTO (part title)" .)