Answer:
'Use a dictionary or thesaurus'
Step-by-step explanation:
Because, I don't think there is any synonyms in that sentence for that word or anything that gives you a hint about the unknown word meaning, but, if I would make a guess I would say that the following sentence, "No one else had been clever enough to figure it out" would say something about the 'unknown meaning' word. However, usually if I see a word that I can't find its meaning in the following sentence, I would just look up its meaning or find synonyms of that word.