Hole in vessel, it capsizing – transport in 20 (9)

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

PORE(a minute hole/opening in a surface) contained in ( in ) VAT(a vessel/tank used to hold liquid) + reversal of ( … capsizing , in a down clue) IT. Defn: …, ie. in solution to 20 down.