Barely, scarcely (6)
I believe the answer is:
hardly
This clue is a double definition.
'barely' is the first definition.
(I know that barely can be written as hardly)
'scarcely' is the second definition.
(I know that scarcely can be written as hardly)
(Other definitions for hardly that I've seen before include "With great difficulty" , "Not much" , "Barely, scarcely" , "Not quite "It seems unlikely!"" , "Almost not" .)