One virtuous person into the beer becomes frantic (10)
I believe the answer is:
distraught
'frantic' is the definition.
(I've seen this in another clue)
'one virtuous person into the beer' is the wordplay.
'one' becomes 'i' (Roman numeral).
'virtuous person' becomes 'st' (saint).
'into' indicates putting letters inside.
'the beer' becomes 'draught' (draught beer is a type of beer).
'i'+'st'='ist'
'ist' put inside 'draught' is 'DISTRAUGHT'.
'becomes' acts as a link.
(Other definitions for distraught that I've seen before include "At one's wits - end" , "Greatly agitated in mind - hits at drug (anag)" , "Beside oneself" , "Having got the wind up" , "wild" .)