Tucking into bread with sweet topping, king had a merry time (9)

'had a merry time' is the definition.
Although both the answer and definition are past participle verbs, I cannot understand how one could define the other.

'tucking into bread with sweet topping king' is the wordplay.
'tucking into' is an insertion indicator.
'bread' becomes 'roll' (roll is a kind of bread).
'with sweet topping' becomes 'iced' (I am not sure about this - if you are sure you should believe this answer much more).
'king' becomes 'K' (abbreviation for king in chess).
'roll'+'iced'='rolliced'
'rolliced' enclosing 'k' is 'ROLLICKED'.

Can you help me to learn more?