Barely changes a couple of letters (6)
I believe the answer is:
hardly
'barely' is the definition.
(synonyms)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for hardly that I've seen before include "With great difficulty" , "Almost not" , "Not much" , "Barely, scarcely" , "Not quite "It seems unlikely!"" .)