Disparaging copper caught up in traffic (9)
I believe the answer is:
traducing
'disparaging copper' is the definition.
'traducing' can be an answer for 'disparaging'. I am unsure of the 'copper' bit.
'caught up in traffic' is the wordplay.
'caught' becomes 'cu' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'up' is a reversal indicator (in down clue: letters go upwards).
'in' indicates putting letters inside.
'traffic' becomes 'trading'.
'cu' backwards is 'uc'.
'uc' going inside 'trading' is 'TRADUCING'.
(Another definition for traducing that I've seen is " Speaking badly of".)