Tree and metal-bearing rock on land (6)
I believe the answer is:
ashore
'on land' is the definition.
(synonyms)
'tree and metal-bearing rock' is the wordplay.
'tree' becomes 'ash' (ash is a kind of tree).
'and' is a charade indicator (letters next to each other).
'metal-bearing rock' becomes 'ore' (I've seen this before).
'ash'+'ore'='ASHORE'
(Other definitions for ashore that I've seen before include "on terra firma" , "on the coast" , "Off the boat" , "Beached" , "Toward land from water" .)