Cunningly left youngest at law in shady surroundings (5)
I believe the answer is:
slyly
'cunningly' is the definition.
(I know that cunningly can be written as slyly)
'left youngest at law in shady surroundings' is the wordplay.
'left' becomes 'l' (common abbreviation).
'youngest at law' becomes 'y' (I can't justify this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'shady' becomes 'sly' (I've seen this in another clue).
'surroundings' is an insertion indicator.
'y' put into 'sly' is 'slyy'.
'l' put into 'slyy' is 'SLYLY'.
Can you help me to learn more?
(Other definitions for slyly that I've seen before include "in underhand way" , "Craftily, cunningly" , "In a stealthy and secret way" , "In a cunning manner" .)