Unconcealed — in the past tense (5)
I believe the answer is:
overt
'unconcealed' is the definition.
(associated in meaning)
'past tense' is the wordplay.
'past' becomes 'over' (both can mean finished).
'tense' becomes 't' (grammatical abbreviation).
'over'+'t'='OVERT'
'in the' is the link.
(Other definitions for overt that I've seen before include "Plain to see - manifest" , "Trove (anag.)" , "Openly displayed" , "Open and observable" , "Done or shown openly" .)