Is it permitted to order clothing online during the 9 days if it will arrive and be worn only after tisha baav?
What if the stuff is needed directly after tisha baav and cannot wait to be ordered after the 9 days?
Essentially it is problematic even to order clothing that will be delivered after the nine days, because the actual buying of the clothes is diverting one’s attention from the aveilus. However, if you will not be able to get it unless it is ordered during the nine days, then it would be considered like a davar ha’aved and it would be permitted.
Shulchan Aruch O”CH 551-7, M:B 551-49, 11, Kovetz Halachos (Bein Hamitzarim) 12-3, Poskim.