Garment Christopher has left inside (4)
I believe the answer is:
kilt
'garment' is the definition.
(kilt is a kind of garment)
'christopher has left inside' is the wordplay.
I cannot quite understand how this works, but
'left' could be 'l' (common abbreviation) and 'l' is found in the answer.
'christopher' could be 'kit' (short for Christopher) and 'kit' is found within the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for kilt that I've seen before include "Mac's skirt" , "Scotsman's garb" , "Under which, traditionally, a Scotsman wears nothing" , "Highland garment" , "Checked menswear" .)