Clarity Ferm is a solution, supplied in 10ml tubes, that contains "proline-specific endo-protease derived from a selected strain of Aspergillus niger". It basically chops up proteins (polypeptides) to stop the formation of "chill haze" and and as a useful side effect it chops up gluten proteins to make gluten free beer (interesting!).
This enzyme is not notified as poisonous in elevated quantities and would probably denature anyway in very acidic conditions (think stomach acid).
From the manufacturers spec sheet I see that 10ml is good for 5 gallons. So using 5ml in 1 gallon is not a vast "overdose". I note that the recommended dosage is doubled for beers with >20% wheat in the grain bill. So it can be used in greater and lesser amounts.
IMHO I would bottle and condition the beer to allow the enzyme to work on the gluten. After a few months I would sample it.