Very enjoyable grid, though I didn't get the caster connection even with the group correctly formed; and for the uncle connection I would not have been able to resist using telegram. Great puzzle, as usual; hank you.

@RossChris: I have to admit 'Telegram' didn't even come to mind (to my shame!), although I would definitely use it if I was making the grid again. Thanks!

pretty good except for the (non) homophones.

Good... as always! Missed the homophones... although not 100% convinced by serious.

Only 3 out of the 4 "homophones" actually are.

@Paddy @FirstGofer @bonehead: I think homophones are somewhat dependent on accent/pronunciation, so that may be where the difference of opinion has sprung from. As three of you have raised it as an issue, however, I will take it on the chin as a flaw in this grid. Please award yourselves additional point/s as you see fit, and I'll be more careful next time! :-)

7/10 got the homophone one right (based on a hopeful guess, due to pronunciation differences), don't see it as that big a deal. Got the zebra line but no clue as to meaning (a cultural thing) after eliminating T.
I think this was pretty good..

Unravelled the groups and managed three connections but I was nowhere near the fourth. Thanks for the challenge!