Triathlon is a fun competition for kids? (5-6,4)
I believe the answer is:
three-legged race
'triathlon is a fun' is the definition.
I can't judge whether this defines the answer.
'competition for kids?' is the wordplay.
I cannot really understand how this works, but
'competition' could be 'race' (race is a kind of competition) and 'race' is located in the answer.
The remaining letters 'threelegged' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for three-legged race that I've seen before include "Its entrants are bound" , "Sports event for pairs" .)