Artifices not left with customs (5)
I believe the answer is:
ruses
'artifices' is the definition.
(I know this)
'not left with customs' is the wordplay.
'not left' becomes 'r' (abbreviation for right).
'with' says to put letters next to each other.
'customs' becomes 'uses' (use is a kind of custom).
'r'+'uses'='RUSES'
(Other definitions for ruses that I've seen before include "Stratagem designed to deceive" , "Clever stratagems" , "Tricks or deceptions" , "Clever plans designed to deceive" , "'Stratagems, tricks (5)'" .)