Give way about a source of ore (4,2)
I believe the answer is:
cave in
'give way' is the definition.
(both can mean to collapse)
'about a source of ore' is the wordplay.
'about' becomes 'ca' (abbreviation for 'circa').
'a source of ore' becomes 'vein' (as in a vein in a rock).
'ca'+'vein'='CAVE-IN'
(Other definitions for cave in that I've seen before include "Yield to outside pressure" , "Subside, collapse" , "(Roof) collapse; abandon resistance" , "(Opposition, roof) collapse" , "Collapse of, eg, tunnel" .)