Crossword Genius

Copper's covering evidence (5)


I believe the answer is:

'evidence' is the definition.
(proof is a kind of evidence)

'copper's covering' is the wordplay.
'copper' becomes 'p'.
'covering' becomes 'roof' (roof is a kind of covering).

(Other definitions for proof that I've seen before include "Specimen", "Conclusive demonstration", "may need amending", "a writer may check", "Render impervious (to)".)

I've seen this clue in The Independent.