Metal barrel gents renovated (8)
I believe the answer is:
tungsten
'metal' is the definition.
(I know that tungsten is a type of metal)
'barrel gents renovated' is the wordplay.
'barrel' becomes 'tun' (tun is a kind of barrel).
'renovated' indicates anagramming the letters.
'gents' is an anagram of 'gsten'.
'tun'+'gsten'='TUNGSTEN'
(Other definitions for tungsten that I've seen before include "Rare metallic element" , "Wolfram" , "Hard metal used in lamps etc" , "Hard metal used in steels" , "Chemical element, symbol W" .)