Lacking the top characters on most sides today (7)
I believe the answer is:
without
'lacking' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for without that I've seen before include "Lacking; outside" , "Not accompanied by" , "Free from: in the absence of" , "Lacking; not inside" .)