Betting system involving American lawyer until now (2,4)
I believe the answer is:
to date
'until now' is the definition.
(I've seen this in another clue)
'betting system involving american lawyer' is the wordplay.
'betting system' becomes 'tote' (I've seen this before).
'involving' means one lot of letters goes inside another.
'american lawyer' becomes 'DA' (abbreviation for 'District Attorney').
'tote' going around 'da' is 'TO DATE'.
(Other definitions for to date that I've seen before include "Thus far" , "Until this point in time" , "Reason suitor's come" , "Up until today" , "Amorous American's aim," .)