Reportedly a tiny hole is unacceptable (4)
I believe the answer is:
poor
'unacceptable' is the definition.
(I've seen this in another clue)
'reportedly a tiny hole' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'a tiny hole' becomes 'pore' (I've seen this in another clue).
'pore' sounds like 'POOR'.
'is' acts as a link.
(Other definitions for poor that I've seen before include "(Person) with little money" , "Of inferior standard" , "Mere" , "Lacking means; paltry" , "Hard-up" .)