What does the cryptic crossword clue "Tells everyone about speed where planes fly (8)" mean?

The wordplay uses a charade (building blocks). AIRS (synonym="‘tells everyone about’") + PACE (synonym="‘speed’") = AIRSPACE The answer is AIRSPACE.

Tells everyone about speed where planes fly (8)

Guardian Cryptic #29468 | 4 Down | 2024-08-22 flower