Seize part of royal bride's dress (8)

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

DI’S (royal bride’s) TRAIN, which was 25 ft long – see here – I didn’t think I had met this word before but (cf restrain(t) as above and constrain(t)), I remembered, from my A Level History, the old law Distraint of Knighthood, resurrected by Charles I to raise money during his Personal Rule without recalling Parliament