One possibly charging a flat fee? (8)
I believe the answer is:
landlord
'flat fee?' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'one possibly charging a' is the wordplay.
I cannot quite see how this works, but
'one' could be 'o' (I've seen this in other clues) and 'o' is found within the answer.
'a' could be 'an' and 'an' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for landlord that I've seen before include "One leasing property" , "Mein host" , "One with property for rent" , "Innkeeper" , "Publican" .)