Historic accessory for boy’s clothes? I’d look almost silly (3,6,3)
I believe the answer is:
old school tie
'historic accessory for boy's clothes?' is the definition.
(tie worn by ex-pupils of a particular school)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for old school tie that I've seen before include "A source of unfair advantage" , "Upper-class emblem of loyalty" , "Loyalty of those educated together" , "Perceived social and business network based on education" , "Term for group loyalty of those with posh private eduction" .)