Short, positive response returned by son shows respect (8)
I believe the answer is:
curtseys
'response returned by son shows respect' is the definition.
I can't tell whether this definition defines the answer.
'short positive' is the wordplay.
'short' becomes 'curt' (synonyms).
'positive' becomes 'seys' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'curt'+'seys'='CURTSEYS'
Can you help me to learn more?
(Another definition for curtseys that I've seen is " Kind of bows by women, bending the knees".)