Naughty child meeting a large American animal (6)
I believe the answer is:
impala
'animal' is the definition.
(I've seen this before)
'naughty child meeting a large american' is the wordplay.
'naughty child' becomes 'imp' (informal term for a misbehaving child).
'meeting' says to put letters next to each other.
'large' becomes 'l'.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'imp'+'a'+'l'+'a'='IMPALA'
(Other definitions for impala that I've seen before include "'African antelope, takes great leaps (6)'" , "horny creature" , "Antelope with lyre-shaped horns" , "Graceful antelope" , "game animal" .)