It was...that 是定语从句，还是强调句辨析？

He told me with grim humour of the time he had spent acting as guide to Cockneys who wanted to see the night side of life in Paris; it was an occupation that appealed to his sardonic temper and somehow or other he had acquired a wide acquaintance with the more disreputable quarters of the city. He told me of the long hours he spent walking about the Boulevard de la Madeleine on the look-out for Englishmen, preferably the worse for liquor, who desired to see things which the law forbade. When in luck he was able to make a tidy sum; but the shabbiness of his clothes at last frightened the sight-seers, and he could not find people adventurous enough to trust themselves to him. Then he happened on a job to translate the adverti百度竞价推广ents of patent medicines which were sent broadcast to the medical profession in England. During a strike he had been employed as a house-painter.

请教老师：这一句 it was an occupation that appealed to his sardonic temper and somehow or other he had acquired a wide acquaintance with the more disreputable quarters of the city.是定语从句，而非强调句吧？

it 指代前面的guide吗？ 但为何不是acting as a guide, 而是acting as guide呢？还有，最后一句出现的sent broadcast没了解，这里的broadcast如何理解剖析呢？

1.  it was an occupation that appealed to his sardonic temper and somehow or other he had acquired a wide acquaintance with the more disreputable quarters of the city.
it 指代前文的 acting as guide 或 guide 均可，由于表语是“职业”。你既然已经了解 it 是代词，那就是定语从句。你为什么还怀疑是否强调句？除此之外，黑体部分与讨论的问题无关，是并列分句，为什么写在问题中。
提醒：你这种问法实在不可取，你了解为何吗——it was an occupation that appealed to his sardonic temper and somehow or other he had acquired a wide acquaintance with the more disreputable quarters of the city.是定语从句，而非强调句吧？

2. as + 身份或职业名词，可以省略冠词。

3. broadcast 是副词，修饰 sent，说明 sent 的方法。意思是：经广播；广泛地，到处，四面八方；散布地，四散地。