King who went away with heavy heart (4)
I believe the answer is:
offa
'king who went' is the definition.
'offa' can be an answer for 'king' (I've seen this before). I'm not certain of the rest of the definition.
'away with heavy heart' is the wordplay.
'away' becomes 'off' (synonyms).
'with' says to put letters next to each other.
'heart' says to take the centre.
The middle of 'heavy' is 'a'.
'off'+'a'='OFFA'
Can you help me to learn more?
(Other definitions for offa that I've seen before include "King of Mercia who gave his name to a dyke" , "Earthwork maker" , "Old dyke-builder" , "man throwing up defence" , "Mercian king, dyke builder" .)