Many thanks, Malone.
I think I must have misunderstood the preamble.
There seems no point in drawing a line through the central unclued entry.
As for the other two lines: one would be the Italian food I alluded to in a previous post and the other might be a 4-letter food provider to be found in the SW quadrant.
A bit of a weak ending to what was a great puzzle - unless of course I've missed something.