Sentence:  Hardly had Mrs. Roebuck driven off when a rusty pick-up truck , father or grandfather of Senor `` Moriarty 's '' Ford sedan , came screeching to a dust swirling stop , and a brown face appeared , its nose threatened by shards of what had <WSD>once</WSD> been the side window . 
Meaning of the word marked with <WSD> tags:  at a previous time;