Removes barriers as protection from the enemy (8)
I believe the answer is:
defences
'protection from the enemy' is the definition.
(defences against an opponent)
'removes barriers' is the wordplay.
'removes' becomes 'de' (I can't explain this - if you can you should believe this answer much more).
'barriers' becomes 'fences' (fence is a kind of barrier).
'de'+'fences'='DEFENCES'
'as' acts as a link.
(Other definitions for defences that I've seen before include "barricades" , "legal cases for those charged" , "ramparts?" , "Protections or justifications" , "Means of protection" .)