What might secure bottom, but not one side (7)
I believe the answer is:
arsenal
'one side' is the definition.
(English football club or side)
I don't understand the remainder of the clue.
(Other definitions for arsenal that I've seen before include "Eleven" , "favoured by some football supporters" , "Collection of weapons" , "array of weapons" , "Where the guns are and who are The Gunners are" .)