Something funny about a boy -- saucy thing (5,5)
I believe the answer is:
salad cream
'something funny' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'about a boy saucy thing' is the wordplay.
'about' is an insertion indicator.
'boy' becomes 'lad' (lad is a kind of boy).
'saucy thing' becomes 'scream' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a'+'lad'='alad'
'alad' put into 'scream' is 'SALAD CREAM'.
Can you help me to learn more?
(Other definitions for salad cream that I've seen before include "Dressing like mayonnaise" , "Sauce" .)