Popular song about king (5)
I believe the answer is:
liked
'popular' is the definition.
(I've seen this before)
'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' (abbreviation for king in chess).
'lied' going around 'k' is 'LIKED'.
(Other definitions for liked that I've seen before include "Was fond of" , "Took pleasure in" , "Enjoyed - popular" , "Appreciated" .)