No! The hall sensor has to be in the magnetic circuit(*), in one of the gaps between
the toriods. The other gap should be bridged with iron or ferrite to continue
the magnetic circuit. But its not a great scheme unless the mechanical positioning
is the same everytime you clamp it on, the exact spacing of the gap in the magnetic
field dominates the behaviour (gaps always dominate magnetic circuits).
(*) The flux flows round the toroid.
If you don't need to clamp-on, you can take a one-piece ferrite toriod and cut
a slot through it with a diamond wheel to take the sensor - the result has
fixed dimensions and can be calibrated. But you have to thread the wire
through the toroid.
Again, a small clamp CT from a power monitor unit is a simpler option, easy to
find these days as extra probes are often sold separately.