Sounds of wonder/sounds of slime (4)
I believe the answer is:
oohs
'sounds of wondersounds' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'of slime' is the wordplay.
'of' becomes 'o''.
'slime' becomes 'ohs' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'o'+'ohs'='OOHS'
Can you help me to learn more?
(Other definitions for oohs that I've seen before include "With aahs, they're expressions of delight" , "Exclamations of surprise, shoo away" .)