Detective's London address in song (5,6)
I believe the answer is:
baker street
'song' is the definition.
I know nothing about this answer so I can't judge whether this works.
'detective's london address' is the wordplay.
'detective's london' becomes 'baker' (I can't justify this - if you can you should give a lot more credence to this answer).
'address' becomes 'street' (street address is a kind of address).
'baker'+'street'='BAKER STREET'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for baker street that I've seen before include "Where Sherlock Holmes lived" , "tube station" , "Clue solver's way" , "London home of detective" , "1978 Gerry Rafferty song" .)