Disjointed; rambling (10)
I believe the answer is:
incoherent
This clue is a double definition.
'disjointed' is the first definition.
(similar in meaning)
'rambling' is the second definition.
(similar in meaning)
(Other definitions for incoherent that I've seen before include "Confused" , "Internally inconsistent" , "difficult to understand" , "drunk?" , "Unintelligible" .)