Exhausted, it is clear, by the bumpy ride (9)
I believe the answer is:
overtired
'exhausted' is the definition.
(I've seen this before)
'clear by the bumpy ride' is the wordplay.
'clear' becomes 'overt' (both can mean apparent or obvious).
'by' means one lot of letters go next to another.
'the bumpy' indicates anagramming the letters (letters get bumped around).
'ride' anagrammed gives 'ired'.
'overt'+'ired'='OVERTIRED'
'it is' acts as a link.
(Other definitions for overtired that I've seen before include "Exhausted" , "needing sleep" , "whacked" .)