Good person speaks and falters (8)
I believe the answer is:
stutters
'falters' is the definition.
('stutter' can be a synonym of 'falter')
'good person speaks' is the wordplay.
'good person' becomes 'st' (saint).
'speaks' becomes 'utters' ('utter' can be a synonym of 'speak').
'st'+'utters'='STUTTERS'
'and' is the link.
(Other definitions for stutters that I've seen before include "impediments" , "Speaks haltingly" , "falters" , "Speaks with hesitant repetition of first consonants" , "Stammers in repeating the first consonants of words" .)