Bore dropping bible in part of 8 twice (4)

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

This had to be CITY from the crossers and definition, and to make sense of the reference in 28a, but it took me a very long time to parse it. I think it’s C [av] ITY (bore = hollowed-out interior), dropping out AV (abbreviation for the Authorised Version of the Bible). Reference to 8a LINE: part of the names of two London Underground lines, as noted in 17a (Hammersmith & City) and 24a (Waterloo & City).