Walker on water has think about tricky task (4-6)

'walker on water' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'think about tricky task' is the wordplay.
'think' becomes 'ponder' (pondering is a kind of thinking).
'about' means one lot of letters goes inside another.
'tricky' indicates an anagram.
'task' anagrammed gives 'skat'.
'ponder' going around 'skat' is 'POND-SKATER'.

'has' is the link.

Can you help me to learn more?