Outsize M&S skirts for British supermodel (4)
I believe the answer is:
moss
'british supermodel' is the definition.
I can't tell whether this defines the answer.
'outsize ms skirts' is the wordplay.
'outsize' becomes 'os'.
'skirts' is an insertion indicator (skirt can mean to go around).
'os' inserted within 'ms' is 'MOSS'.
'for' is the link.
Can you help me to learn more?
(Other definitions for moss that I've seen before include "Stirling or Kate?" , "Plant growing in dense mats" , "Veteran racing driver" , "English racing driver, b. 1929" , "that may hug trees?" .)