Store in stronghold (4)
I believe the answer is:
keep
This clue is a double definition.
'store' is the first definition.
(thesaurus)
'stronghold' is the second definition.
(keep is a kind of stronghold)
'in' acts as a link.
(Other definitions for keep that I've seen before include "Retain; part of castle" , "Act as custodian of" , "run" , "Fort" , "Look after" .)