Pickle from the south-west reportedly concerning (9)
I believe the answer is:
cornichon
'pickle from the south-west reportedly concerning' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'pickle from the south-west reportedly concerning' is the wordplay.
'pickle' becomes 'corn' (I've seen this in another clue).
'from the south' says the letters should be written backwards (in a down clue, letters go up).
'west reportedly' becomes 'hci' (I can't explain this - if you can you should give a lot more credence to this answer).
'concerning' becomes 'on' (both can mean 'in relation to').
'hci' in reverse letter order is 'ich'.
'corn'+'ich'+'on'='CORNICHON'
Can you help me to learn more?
(Another definition for cornichon that I've seen is " Type of small gherkin".)