Is there a simple script to delay audio play back, till a certain time within a scene?.
Use yield and WaitForSeconds:
function Start () {
yield WaitForSeconds(10.0);
audio.Play();
}
If you control the playing of the clip in code, it's a simple case of setting up a check against Time.time (seconds since game loaded) or Time.timeSinceLevelLoad (self explanatory) and playing the clip once this exceeds a value. You'll need to have a check to see if it isn't playing already, or a bool that tells you you've already played it.
A bare-bones example of a ten-second delay:
if (Time.timeSinceLevelLoad > 10 && !playedIt) {
audio.Play();
playedIt = true;
}