Working dog on run — one seen with blackened face? (7)
I believe the answer is:
collier
'one seen with blackened face?' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'working dog on run' is the wordplay.
'working dog' becomes 'collie' (collie is a kind of working dog).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'run' becomes 'r' (cricket abbreviation).
'collie'+'r'='COLLIER'
Can you help me to learn more?
(Other definitions for collier that I've seen before include "Cargo ship" , "British coal-miner" , "He works in a coal mine" , "Miner; coal ship" , "Geordie Jack, commonly" .)