Genuine rut developed, to a point (4)
I believe the answer is:
true
'genuine' is the definition.
(I know that genuine can be written as true)
'rut developed to a point' is the wordplay.
'developed' indicates anagramming the letters.
'to a point' becomes 'e' (compass point).
'rut' with letters rearranged gives 'tru'.
'tru'+'e'='TRUE'
(Other definitions for true that I've seen before include "Unfeigned" , "Veracious" , "Agreeing with fact or reality" , "Dependable -- loyal" , "Real; accurate" .)