Modest shaded avenue heading South? Quite the reverse (5)
I believe the answer is:
small
'modest' is the definition.
(thesaurus)
'shaded avenue heading south? quite the reverse' is the wordplay.
I cannot really understand how this works, but
'south?' could be 's' (abbreviation) and 's' is found in the answer.
'quite' could be 'all' (I've seen this in another clue) and 'all' is present in the answer.
A single letter 'm' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for small that I've seen before include "Not fully grown" , "Social chat" , "Lower middle of the back" , "Insignificant; young" , "Brief" .)