Confer Oscar on writer and actors of mine (4-4)

'mine' is the definition.
(mining minerals from the surface)

'confer oscar on writer and actors' is the wordplay.
'confer oscar on' becomes 'o' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'writer' becomes 'pen' (something which writes).
'and' means one lot of letters go next to another.
'actors' becomes 'cast' (group of actors).
'o'+'pen'+'cast'='OPEN-CAST'

'of' is the link.

Can you help me to learn more?