Why the children are unruly at first (7)
I believe the answer is:
reasons
'why the' is the definition.
I can't judge whether this defines the answer.
'children are unruly at first' is the wordplay.
'children' becomes 'sons' (son is a kind of child).
'unruly' indicates an anagram.
'at first' says to put letters next to each other.
'are' anagrammed gives 'rea'.
'sons' after 'rea' is 'REASONS'.
Can you help me to learn more?
(Other definitions for reasons that I've seen before include "Motives, explanations" , "Justifications or motives" , "Ness oar (anag.)" , "Period of reduced economic activity" , "Thinks logically" .)