Exercise unavailable? Definitely not (4)
I believe the answer is:
nope
'exercise unavailable? definitely not' is the definition.
I can't tell whether this defines the answer.
'exercise unavailable? definitely not' is the wordplay.
I cannot really see how this works, but
'exercise' could be 'pe' (Physical Education) and 'pe' is present in the answer.
'not' could be 'no' (negative) and 'no' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for nope that I've seen before include "Certainly not" , "Negative response" , "You must be joking" , "Not on your life!" , "definitely not!" .)