20 a Is the monster heady? Quite the opposite, it appears. (5) H-R-Y. Is the answer HORNY and if so why?
23 a Arrive at the junction with a blazer. (5) C-M-O.
Is the answer CAMEO and if so why?
A different angle.... I'm thinking it may be Herry Monster from Sesame Street. The clue says 'it appears' suggesting a play on Herry/Hairy. Hairy could be interpreted as an opposite of heady.....