The tricky bit would be parting him from the Hound.

What we want you to do is quite a tricky bit of work.

This is the tricky bit, though - where does the money to fund that spending come from?

Now this is where the tricky bit comes in.

Thinking of something interesting to say each time you blog is the tricky bit.

I had just got to the tricky bit when in walked this friend with the usual enquiries.

The only tricky bit is that you already have an object in the air while you're doing it.

This was going to be one tricky bit of flying.

But getting in touch with them is the tricky bit.

It might've been an hour later and him at the trickiest bit of his day.