Run down origin of iconic jar by study (9)
I believe the answer is:
denigrate
'run down' is the definition.
(I've seen this before)
'origin of iconic jar by study' is the wordplay.
'origin of' indicates taking the first letters.
'jar' becomes 'grate' (make unpleasant sound).
'by' means one lot of letters go next to another.
'study' becomes 'den' (I've seen this before).
The first letter of 'iconic' is 'i'.
'i'+'grate'='igrate'
'igrate' after 'den' is 'DENIGRATE'.
(Other definitions for denigrate that I've seen before include "Disparage" , "Slight" , "Bad-mouth" , "Blacken" , "put down" .)