Bad liar cites sensible... (9)
I believe the answer is:
realistic
'sensible' is the definition.
(I've seen this in another clue)
'bad liar cites' is the wordplay.
'bad' indicates an anagram.
'liar'+'cites'='liarcites'
'liarcites' anagrammed gives 'REALISTIC'.
(Other definitions for realistic that I've seen before include "Down-to-earth" , "It is clear, being practical and sensible" , "true-to-life" , "believable" , "Pragmatic" .)