Silly way to split rent? Crazy (7)
I believe the answer is:
haywire
'crazy' is the definition.
(I've seen this before)
'silly way to split rent?' is the wordplay.
'silly' indicates anagramming the letters.
'to split' means one lot of letters goes inside another.
'rent?' becomes 'hire' (I've seen this before**).
'way' anagrammed gives 'ayw'.
'ayw' going within 'hire' is 'HAYWIRE'.
(Other definitions for haywire that I've seen before include "nuts" , "Out of order -- erratic" , "Malfunctioning badly" , "Mad" , "Crazy - not functioning properly" .)