Child, rather cutesy, to swim across the Channel (9)
I believe the answer is:
tweenager
'child' is the definition.
(I have seen 'Precocious child' mean 'tweenager' so perhaps 'child' could also mean 'tweenager')
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for tweenager that I've seen before include "Possibly a ten-year-old" , "adolescent" , "Youngster" , "(Informally) a child approaching the age of 13?" , "Precocious child" .)