Handled transaction on time (5)
I believe the answer is:
dealt
'handled' is the definition.
(dealing is a kind of handling)
'transaction on time' is the wordplay.
'transaction' becomes 'deal' (a deal is a transaction or exchange).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'time' becomes 't' (abbreviation).
'deal'+'t'='DEALT'
(Other definitions for dealt that I've seen before include "Distributed playing cards" , "Gave out playing cards" , "Carried out business" , "Traded" , "Delta (anag.)" .)