King at head of very happy family (7)
I believe the answer is:
related
'king at head of very happy family' is the definition.
I can't judge whether this definition defines the answer.
'king at head of very happy' is the wordplay.
'king' becomes 'R' (abbreviation of Latin rex).
'at head of' means one lot of letters go next to another (some letters go in front of others).
'very happy' becomes 'elated' (I've seen this before).
'r'+'elated'='RELATED'
Can you help me to learn more?
(Other definitions for related that I've seen before include "Connected by family ties" , "Connected, by kinship say" , "within family" , "of one family" , "spilled the beans" .)