The chap’s showing no repetition of disapproving noise (3)
I believe the answer is:
his
'the chap's showing no repetition of disapproving noise' is the definition.
I can't tell whether this definition defines the answer.
'the chap's showing no' is the wordplay.
'the chap' becomes 'Hi'.
'showing no' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'hi'+'s'='HIS'
Can you help me to learn more?
(Other definitions for his that I've seen before include "Belonging to the male" , "Belonging to that man" , "that chap's" , "It belongs to him" , "That man's" .)