Mum interrupts Dad with expression of contempt (5)
I believe the answer is:
pshaw
'expression of contempt' is the definition.
(I've seen this before)
'mum interrupts dad' is the wordplay.
'mum' becomes 'sh' (I've seen this in other clues).
'interrupts' is an insertion indicator.
'dad' becomes 'paw' (I can't explain this - if you can you should believe this answer much more).
'sh' placed into 'paw' is 'PSHAW'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for pshaw that I've seen before include "Expression of contempt" , "scornful reaction" , "Exclamation of contempt" , "Contemptuous expression" , "Contemptuous riposte" .)