45a, guess when piping presumably protected from floods crosses road finally (1,4,2,3,4) no idea! Guessing something like " a shot in the dark" ... Enlighten me please, someone!
Guess - A Shot In The Dark (as hot = piping, in the ark = protected from floods, d - 'roaD' (finally, last letter).The 'd' goes in/'crosses' 'in the ark'