Mixed-up clothing came first (7)
I believe the answer is:
garbled
'mixed-up' is the definition.
(I've seen this before)
'clothing came first' is the wordplay.
'clothing' becomes 'garb' (garb is a kind of clothing).
'came first' becomes 'led' (to lead is to go first).
'garb'+'led'='GARBLED'
(Other definitions for garbled that I've seen before include "Confused, disjointed" , "(Message) corrupted" , "Unintentionally jumbled" , "Mixed-up" , "Disjointed, incoherent" .)