Carlos may be out of breath, but he's learning (7)
I believe the answer is:
scholar
'he's learning' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'carlos may be out of breath' is the wordplay.
'may be' indicates anagramming the letters.
'out of' means one lot of letters goes inside another (some letters on the outside of others).
'breath' becomes 'h' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'carlos' with letters rearranged gives 'scolar'.
'scolar' enclosing 'h' is 'SCHOLAR'.
'but' acts as a link.
Can you help me to learn more?
(Other definitions for scholar that I've seen before include "Academic; pupil" , "Learned type" , "Learned (or learning) one" , "Pupil - erudite person" , "university type?" .)