Startled schoolmaster forced to speak (9)
I believe the answer is:
surprised
'startled schoolmaster' is the definition.
'surprised' can be an answer for 'startled' (I've seen this before). I am not sure about the 'schoolmaster' bit.
'forced to speak' is the wordplay.
'forced' becomes 'prised' (I've seen this in other clues).
'to' means one lot of letters go next to another (I've seen this in other clues).
'speak' becomes 'sur' (I can't justify this - if you can you should believe this answer much more).
'prised' after 'sur' is 'SURPRISED'.
(Other definitions for surprised that I've seen before include "Lost for words" , "Shocked" , "Startled" , "Mildly astonished" , "Astounded" .)