@script RequireComponent(AudioSource)
    function Start() {
        if(!audio.playOnAwake) {
            audio.Play(); // Play the clip if it wasn't set to play on awake
    }
}

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(AudioSource))]
public class example : MonoBehaviour {
    void Start() {
        if (!audio.playOnAwake)
            audio.Play();
        
    }
}

import UnityEngine
import System.Collections

[RequireComponent(AudioSource)]
class example(MonoBehaviour):

    def Start():
        if not audio.playOnAwake:
            audio.Play()