Finished on time and now open (5)
I believe the answer is:
overt
'now open' is the definition.
'overt' can be an answer for 'open' (synonyms). I am not certain of the 'now' bit.
'finished on time' is the wordplay.
'finished' becomes 'over' (over can mean finished or ended).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'time' becomes 't' (abbreviation).
'over'+'t'='OVERT'
'and' is the link.
Can you help me to learn more?
(Other definitions for overt that I've seen before include "Open and unconcealed" , "Voter (anag.)" , "Obvious, patent" , "Open and candid" , "This is not hard to see" .)