There's a degree of decadence in port (4)
I believe the answer is:
aden
'port' is the definition.
(port in Yemen)
'there's a degree of decadence' is the wordplay.
'ADEN' is hidden in amongst the letters.
However, I'm uncertain how this is indicated.
'in' is the link.
Can you help me to learn more?
(Other definitions for aden that I've seen before include "Yemeni port" , "Red Sea port" , "Yemeni gulf" , "Commercial capital of Yemen" , "Port city of Yemen" .)