Gets closer from one arsenal (5)
I believe the answer is:
nears
'gets closer' is the definition.
(to near is to approach or get closer)
'from one arsenal' is the wordplay.
'from' indicates the answer is hidden within the clue.
'NEARS' is hidden in the letters of 'one arsenal'.
(Other definitions for nears that I've seen before include "Uses snare to get closer" , "advances" , "Moves closer to" , "Comes closer" , "Draws closer to" .)