One visiting sailor, lover of pop perhaps and heavy metal (6)
I believe the answer is:
osmium
'heavy metal' is the definition.
(I've seen this before)
'one visiting sailor lover of pop' is the wordplay.
'one' becomes 'i' (Roman numeral).
'visiting' means one lot of letters goes inside another.
'sailor' becomes 'os' (ordinary seaman).
'lover of pop' becomes 'mum' (I can't explain this - if you can you should believe this answer much more).
'os'+'mum'='osmum'
'i' placed into 'osmum' is 'OSMIUM'.
'perhaps and' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for osmium that I've seen before include "The heaviest metal known" , "Lustrous, extremely hard member of the platinum metals group" , "Heavy metal" , "Densest of all naturally occurring metallic elements, Os" , "Metal, the densest natural element (symbol Os)" .)