What does the cryptic crossword clue "3 vehicle clamped in Kensington Gardens (5)" mean?

The definition is "3 vehicle". The wordplay uses a hidden word. Hidden in "3 vehicle clamped in kensingTON GArdens" The answer is TONGA.

3 vehicle clamped in Kensington Gardens (5)

Guardian Cryptic #28779 | 9 Across | 2022-06-09 flower