Toss-up about arrangement for arts in remedial centre (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

LOB (toss-up) reversed or ‘about’ with an anagram (‘arrangement’) of ARTS inside or ‘in’. We first thought that this was parsed as LOB (toss) with up as the reversal indicator and ‘about’ as the inclusion indictor. However, it’s an across clue so it wouldn’t work.