A hideous argument on small London street (6,3)
I believe the answer is:
savile row
'london street' is the definition.
(I've seen this before)
'a hideous argument on small' is the wordplay.
'hideous' becomes 'vile' (I can't justify this - if you can you should give a lot more credence to this answer).
'argument' becomes 'row' (to row is to argue).
'on' says to put letters next to each other.
'small' becomes 's' (abbreviation - e.g. clothes size).
'a'+'vile'+'row'='avilerow'
'avilerow' after 's' is 'SAVILE ROW'.
Can you help me to learn more?
(Other definitions for savile row that I've seen before include "London's tailoring street" , "Street noted for tailoring" , "London tailors' street" , "Fitting way" , "Mayfair street" .)