I need to make a new connection into a 4" clay pipe... unfortunately the
socket has broken with about 2" of the rim missing.

So, I was thinking of gluing the fractured piece (which is to hand) back in
and dropping in a short section of 4" pipe, also 'gluing' that in somehow to
make a watertight seal. Thereafter fitting a connecter for110 mm pipe. There
is an alternative of cutting off the rim off altogether and fitting the
connecter to the section 4" pipe left, but this is very much plan B as this
remaining section is very short (= 1") and if it doesn't work then I'll
really be up the proverbial creek...

So, can anyone suggest a suitable adhesive for the purpose of making a
stong, watertight joint in clay pipe?. I was thinking of using plastic
padding, maybe.

Thanks,
Paul.