Cockney hero heading north, finding gold-bearing rock? (3)
I believe the answer is:
ore
'gold-bearing rock?' is the definition.
(an ore might contain gold)
'cockney hero heading north' is the wordplay.
'cockney hero' becomes 'ero' ('hero' said with the 'H' dropped - a cockney accent.).
'heading north' shows that the letters should be reversed in order.
'ero' backwards is 'ORE'.
'finding' is the link.
(Other definitions for ore that I've seen before include "Solid rock containing metal" , "Deposit of mine" , "Raw material" , "tangle" , "Natural minerals" .)