What does the cryptic crossword clue "What may have poisoned me mad doctor’s to suck out (8)" mean?

The wordplay uses a charade (building blocks). ASP (synonym="poisonous snake") + IRATE (synonym="IRATE") = ASPIRATE The answer is ASPIRATE.

What may have poisoned me mad doctor’s to suck out (8)

Guardian Cryptic #29396 | 15 Down | 2024-05-30 flower