Little Christopher at school that's in poor taste (6)
I believe the answer is:
kitsch
'in poor taste' is the definition.
(similar in meaning)
'little christopher at school' is the wordplay.
'little christopher' becomes 'Kit' (Kit can be short for Christopher).
'at' is a charade indicator (letters next to each other).
'school' becomes 'sch' (common abbreviation).
'kit'+'sch'='KITSCH'
'that's' acts as a link.
(Other definitions for kitsch that I've seen before include "Vulgar, sentimental, art" , "Trash, trashy" , "Garish tasteless art" , "Inferior art" , "Tacky" .)