A little boy swallowing an insect (8)
I believe the answer is:
smidgeon
'a little boy swallowing an insect' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'little boy swallowing an insect' is the wordplay.
'little boy' becomes 'son' (little boy can mean a young son).
'swallowing' means one lot of letters goes inside another.
'an insect' becomes 'midge' (midge is a kind of insect).
'son' enclosing 'midge' is 'SMIDGEON'.
Can you help me to learn more?
(Other definitions for smidgeon that I've seen before include "bit" , "Small amount" , "Very small part" , "A little" , "Tiny amount" .)