Letter to Sakellaropoulou's supporting commoner's figure of speech (9)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

PSI’S (belonging to the Greek letter psi, which is a letter known to the outgoing president of Greece Katerina Sakellaropoulou) after (below, in a down clue = supporting) PROLE (short for proletarian, especially in George Orwell’s 1984 = a commoner rather than an aristocrat). No, I wouldn’t have been able to tell you she was President and had to look up the name, but Eccles is following the standard convention that an obviously Greek name in the wordplay probably means we’re looking at a Greek letter. A figure of rhetorical speech that involves anticipating an objection and countering it before anyone gets the chance to make it. No, I didn’t know that either, but it sounded a convincing enough word to look up . . .