Rambling and thin encore done badly (10)
I believe the answer is:
incoherent
'rambling' is the definition.
('incoherent' can be similar in meaning to 'rambling')
'thin encore done badly' is the wordplay.
'done badly' indicates anagramming the letters (I've seen this in other clues).
'thin'+'encore'='thinencore'
'thinencore' is an anagram of 'INCOHERENT'.
'and' acts as a link.
(Other definitions for incoherent that I've seen before include "Internally inconsistent" , "Confused" , "drunk?" , "Unintelligible" , "rambling" .)