Metal suit (6)
(Other definitions for armour that I've seen before include "Protective body-plating" , "Protection for a fighter" , "Greave, sallet and cuirass are pieces of this" , "Protective covering for battle" , "Protective metal covering for combat" .)
'metal suit' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for armor that I've seen before include "US military vehicles" , "protection in America" .)