Damaging tent, guns - metal (8)
I believe the answer is:
tungsten
'metal' is the definition.
(I know that tungsten is a type of metal)
'damaging tent guns' is the wordplay.
'damaging' indicates an anagram.
'tent'+'guns'='tentguns'
'tentguns' is an anagram of 'TUNGSTEN'.
(Other definitions for tungsten that I've seen before include "Metallic element used for lamp filaments" , "Hard metal used in steels" , "Chemical element, symbol W" , "Very hard metal, used in light bulbs" , "Snug tent (anag)" .)