The one in a tent pays rent! (6)
I believe the answer is:
tenant
'pays rent' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'the one in a tent' is the wordplay.
'the one' becomes 'an' (I've seen this in other clues).
'in' is an insertion indicator.
'an' going inside 'tent' is 'TENANT'.
Can you help me to learn more?
(Other definitions for tenant that I've seen before include "Lodger" , "Occupier of rented property" , "Rent-payer" , "Renting occupant" , "individual bound by lease" .)