Christine Sinclair. There’s really no ambiguity about how to say that. That’s pretty clearly a hard /k/ sound in her last name.
Some people call her Sinc. Same consonant sound. No problem.
Now here’s where things get confusing, because there’s no good way to spell her other nickname. The way it usually appears in print preserves the spelling of her name, but violates the rules of English pronunciation. The alternative, using an actual k, looks stupid. Sinky? Okay:
But the thing is, that’s more like how you actually say “Sincy”. Not like this:
Course, people started saying it with the /s/ sound around here, and then other people heard that and started saying it too. I think we should stop and fix it.
It’s easy. Just remember, more like this:
And less like this: