The missing word there is "thought", to form the the phrasal verb "to think of".
If you are having problems identifying a word, try to look at the words around it, and the wider context of the passage. Look at the preposition "of"; are there any phrasal verbs that have "of" at the end that fit the sentence? What does the rest of the text suggest the established musicians did?
Out of interest, what was it about the word that caused you such difficulty? Was it that you were taught English by an English(/Irish)man and the speaker is an American?
[Not a teacher]