Floor rot: yes, that needs repair (6)
I believe the answer is:
storey
'floor' is the definition.
(US term for a floor in a building)
'rot yes that needs repair' is the wordplay.
'that needs repair' indicates an anagram (I've seen this in other clues).
'rot'+'yes'='rotyes'
'rotyes' with letters rearranged gives 'STOREY'.
(Other definitions for storey that I've seen before include "floor of the House" , "Layer of house" , "part of the building" , "Tier of a building" , "Floor or level in a building" .)