There could be about 100 in here, misbehaving
I believe the answer is:
creche
'there could be about 100 in here misbehaving' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'about 100 in here misbehaving' is the wordplay.
'about' becomes 'c' (abbreviation for circa).
'c00' becomes 'c' (Roman numeral).
'in' is an insertion indicator.
'misbehaving' indicates an anagram.
'here' anagrammed gives 'rehe'.
'c' put into 'rehe' is 'reche'.
'c'+'reche'='CRECHE'
Can you help me to learn more?
(Other definitions for creche that I've seen before include "Place to leave children" , "Day nursery for very young children" , "Nursery provided for working parents" , "A day nursery for child-minding" , "Child-minding establishment for working parents" .)