One who can barely run? (8)
I believe the answer is:
streaker
'one who can barely' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'run?' is the wordplay.
I cannot really understand how this works, but
'run?' could be 'streak' (synonyms) and 'streak' is present in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for streaker that I've seen before include "he barely covers the distance" , "One making a dash without clothes" , "Someone running naked in a public place" , "One barely running in public" , "when not having a stitch" .)