Clothing, possibly, including large skirtlike garment (4)
I believe the answer is:
kilt
'skirtlike garment' is the definition.
(kilts are skirt-like garments)
'clothing possibly including large' is the wordplay.
'clothing possibly' becomes 'kit' (kit can mean someone's clothing).
'including' is an insertion indicator.
'large' becomes 'L' (eg in clothes sizes).
'kit' placed around 'l' is 'KILT'.
(Other definitions for kilt that I've seen before include "Bone; circle line" , "Highland garb" , "Highlanders garment" , "Scottish garb" , "Scotsman's garment" .)