Capital Radio occasionally plugs "Rockin' Robin" (7)
I believe the answer is:
nairobi
'capital' is the definition.
(capital of Kenya)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for nairobi that I've seen before include "Badly-behaved child" , "African city" , "East African capital" , "Flat round object" , "I, a robin (anag) - city" .)