A king welcomed by girl’s affected greeting (3,4)
I believe the answer is:
air kiss
'a king welcomed by girl's affected greeting' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'king welcomed by girl's affected greeting' is the wordplay.
'king' becomes 'R' (abbreviation of Latin rex).
'welcomed by' indicates putting letters inside (letters welcomed inside).
'girl's affected' becomes 'ai' (I can't explain this - if you can you should give a lot more credence to this answer).
'greeting' becomes 'kiss' (I have seen 'Amorous greeting ' mean 'kiss' so perhaps 'greeting' could also mean 'kiss').
'ai'+'kiss'='aikiss'
'r' placed into 'aikiss' is 'AIR-KISS'.
Can you help me to learn more?
(Other definitions for air kiss that I've seen before include "form of greeting" , "Greeting that's not touching" , "contactless transaction" .)