Such service can keep Tommy busy (6)

I believe the answer is:

active

I'm a little stuck... Click here to teach me more about this clue!

'busy' is the definition.
(similar in meaning)

I cannot understand how the rest of the clue works.

(Other definitions for active that I've seen before include "Vigorously moving" , "Moving frequently" , "Keeping busy, not lazy" , "(Of mind) alert, lively" , "Nimble" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.