Stammers (8)
I believe the answer is:
stutters
'stammers' is the definition.
('stutter' can be a synonym of 'stammer')
This is the entire clue.
(Other definitions for stutters that I've seen before include "impediments" , "Stammers in repeating the first consonants of words" , "falters" , "Speaks haltingly" , "Speaks with hesitant repetition of first consonants" .)