Can you give me an example or two of a clausal opener?
When the bus arrived, there was no room to get on.

When the pop start arrived, the crowd went wild

Since the match was delayed, they had time to have something to eat.

Note that clausal openers should not state the obvious. e.g Since he was 18, he wasn't a child anymore.
The weather being mild, we went swimming.
Site Hint: Check out our list of pronunciation videos.
Some clausal openers are:

W- when, w-while, w- where,

A- as

S- since

I- if

A- although

Down the steep slope, the skiier fell.

As dusk fell, she ran into her house.

As I packed my bag I listened to music.

*pop star
Students: We have free audio pronunciation exercises.
Although it was to late

When

While

Where

As

Since

If

Although

Because