Walked around centre of Tokyo, crowded (6)
I believe the answer is:
packed
'crowded' is the definition.
(packing is a kind of crowding)
'walked around centre of tokyo' is the wordplay.
'walked' becomes 'paced' (pacing is a kind of walking).
'around' is an insertion indicator.
'centre of' means to look at the middle letters.
The middle of 'tokyo' is 'k'.
'paced' going around 'k' is 'PACKED'.
(Other definitions for packed that I've seen before include "Crowded" , "Placed clothes etc in suitcase" , "Enveloped" , "Arranged clothes in suitcase for travelling" .)