Scared not to start reprimand (6)
I believe the answer is:
earful
'reprimand' is the definition.
(I know that earful is a type of reprimand)
'scared not to start' is the wordplay.
'scared' becomes 'fearful' (I've seen this in another clue).
'not to start' means to remove the first letter.
'fearful' with its initial letter taken away is 'EARFUL'.
(Other definitions for earful that I've seen before include "harangue" , "A telling-off" , "Spoken reprimand" , "load of wax, possibly" , "Get this and you listen to a lot" .)