Cluster round king for morning meal (6)
I believe the answer is:
brunch
'morning meal' is the definition.
(a cross between breakfast and lunch)
'cluster round king' is the wordplay.
'cluster' becomes 'bunch' (synonyms).
'round' means one lot of letters goes inside another.
'king' becomes 'r' (r is abbreviation for rex).
'bunch' going around 'r' is 'BRUNCH'.
'for' acts as a link.
(Other definitions for brunch that I've seen before include "combined meal" , "Late-morning meal" , "Mid-morning meal" , "Combined breakfast and lunch" , "Portmanteau meal" .)