Metal drum I thrice battered (7)
I believe the answer is:
iridium
'metal' is the definition.
(I know that iridium is a type of metal)
'drum i thrice battered' is the wordplay.
'i thrice' means three replacements for 'i'.
'battered' is an anagram indicator.
'drum'+'i'+'i'+'i'='drumiii'
'drumiii' is an anagram of 'IRIDIUM'.
(Other definitions for iridium that I've seen before include "Colourful compounds come from this" , "number 77" , "Hard metallic element" , "Element, symbol Ir" , "Hard metal element, Ir" .)