Party hosts ending on floor, one over the eight perhaps? (8)
I believe the answer is:
fraction
'one over the eight perhaps?' is the definition.
'party hosts ending on floor' is the wordplay.
'party' becomes 'faction'.
'hosts' means one lot of letters goes inside another.
'ending on floor' becomes 'r' (I can't justify this - if you can you should give a lot more credence to this answer).
'faction' going around 'r' is 'FRACTION'.
(Other definitions for fraction that I've seen before include "little bit" , "Proportional" , "Eg, an eighth" , "may be improper" , "Number of mathematicians" .)