Popular song about king (5)
I believe the answer is:
liked
'popular' is the definition.
(popular means well-liked)
'song about king' is the wordplay.
'song' becomes 'lied' (type of German song).
'about' means one lot of letters goes inside another.
'king' becomes 'K' (chess abbreviation).
'lied' placed around 'k' is 'LIKED'.
(Other definitions for liked that I've seen before include "Was fond of" , "Took pleasure in" , "Enjoyed - popular" , "Appreciated" .)