Possible Clues:

• Flower arrangement for relaxed cream tea? No thanks!
• Cluster in competition with first person
• Flower cluster on a single stem, as in the honey locust
• I challenge you to be first to make a flower arrangement
• Flower cluster (botany)
• Spike resistance with returning tennis player's challenge?
• Aircraftman captured by soldiers demonstrates flower arrangement
• See if you can beat setter's flower arrangement
• Being in blooming form, lets see which of us is the faster