Horrify a very soft little chap (5)
I believe the answer is:
appal
'horrify' is the definition.
(I know that horrify can be written as appal)
'a very soft little chap' is the wordplay.
'very soft' becomes 'pp' (musical abbreviation for pianissimo).
'little' means to remove the last letter (the word is not quite complete).
'chap' becomes 'pal' (I can't justify this - if you can you should believe this answer much more).
'pp' with its last letter removed is 'p'.
'a'+'p'+'pal'='APPAL'
Can you help me to learn more?
(Other definitions for appal that I've seen before include "Greatly dismay" , "Petrify" , "Cause to be unpleasantly surprised" , "Scandalise" , "Disgust" .)