Occupier who pays neither top nor bottom in rent (8)
I believe the answer is:
resident
'occupier' is the definition.
(synonyms)
'pays neither top nor bottom in rent' is the wordplay.
'pays neither' becomes 'reside' (I can't explain this - if you can you should believe this answer much more).
'top' suggests taking the first letters (in a down clue, the first letter is top).
'bottom in' indicates one should take the final letters (in a down clue, the letter at the bottom).
The initial letter of 'nor' is 'n'.
The final letter of 'rent' is 't'.
'reside'+'n'+'t'='RESIDENT'
'who' is the link.
Can you help me to learn more?
(Other definitions for resident that I've seen before include "Occupier" , "Inmate" , "Inhabitant, occupant" , "Inserted by permanent inhabitant" , "Permanent dweller" .)