Copper covered in spots — something he ate? (6)
I believe the answer is:
radish
'something he ate?' is the definition.
(radish is a type of vegetable)
'copper covered in spots' is the wordplay.
'copper' becomes 'DI' (detective inspector, type of copper).
'covered in' means one lot of letters goes inside another.
'spots' becomes 'rash' (as in skin irritation).
'di' going inside 'rash' is 'RADISH'.
(Other definitions for radish that I've seen before include "Root eaten raw in salads" , "Red cold salad ingredient" , "Root vegetable used in salads" , "Small red salad vegetable" , "Hard vegetable" .)