Child at home -- cooler temperature required (6)
I believe the answer is:
infant
'child' is the definition.
(I know that infant is a type of child)
'home cooler temperature required' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'cooler' becomes 'fan' (something which cools).
'temperature' becomes 't' (abbreviation).
'required' means one lot of letters go next to another.
'in'+'fan'+'t'='INFANT'
'at' acts as a link.
(Other definitions for infant that I've seen before include "Very young child or baby" , "Tiny baby" , "Rudimentary" , "Babe" , "Toddler" .)