Off the cuff I am on time - they say you follow! (9)
I believe the answer is:
impromptu
'off the cuff' is the definition.
(I've seen this before)
'i am on time they say you follow' is the wordplay.
'i am' becomes 'I'm' (contraction).
'on time' becomes 'prompt' (synonyms).
'they say' indicates a 'sounds like' (homophone) clue.
'follow' says to put letters next to each other.
'you' is a homophone of 'u'.
'im'+'prompt'+'u'='IMPROMPTU'
(Other definitions for impromptu that I've seen before include "Without much planning" , "On the spur of the moment" , "Improvised" , "Unprepared" , "Piano piece" .)