Clothing was first to be mixed up (7)
I believe the answer is:
garbled
'be mixed up' is the definition.
(I've seen this in another clue)
'clothing was first' is the wordplay.
'clothing' becomes 'garb' (garb is a kind of clothing).
'was first' becomes 'led' (to lead is to go first).
'garb'+'led'='GARBLED'
'to' is the link.
(Other definitions for garbled that I've seen before include "(Message) corrupted" , "Distorted - muddled" , "Disjointed, incoherent" , "Distorted, confused" , "Unintentionally jumbled" .)