Suit of mail (6)
I believe the answer is:
armour
'suit of mail' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for armour that I've seen before include "king caught in affair" , "Greave, sallet and cuirass are pieces of this" , "Protective covering for battle" , "Protective metal covering for combat" , "Soldier's body protection" .)