One who may be barely visible (6)
I believe the answer is:
nudist
This clue could be a double definition.
'one who may be barely' is the first definition.
The answer is a person as well as being a singular noun. This is suggested by the definition. I also know that 'barely' relates to this answer.
'visible' is the second definition.
Although both the answer and definition are adjectives, I don't see how they can define each other.
Can you help me to learn more?
(Other definitions for nudist that I've seen before include "Person who discards clothes out of conviction" , "one economising on clothes" , "Person committed to going unclothed" , "I want to be 12 [NAKED]" , "S/he prefers to be naked" .)