In activity, almost a bustling port? (8)
I believe the answer is:
istanbul
'port?' is the definition.
(I've seen this before)
'in activity almost a bustling' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for istanbul that I've seen before include "Nail bust in the Turkish city" , "Eurasian city" , "City in both Europe and Asia" , "City of Turkey" , "It used to be named Constantinople" .)