Army post (4)
'army post' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for base that I've seen before include "'Foundation, bottom (4)'" , "Ignoble; starting point" , "Found - station - contemptible" , "Ignoble - HQ" , "Not a noble" .)
'army post' is the definition.
(a fort is a military post)
This is all the clue.
(Other definitions for fort that I've seen before include "Strategic position" , "Garrison" , "William in Scotland" , "US gold reserves are at - Knox" , "castle, perhaps" .)