Boy embracing Ivan excitedly in celebration (8)
I believe the answer is:
carnival
'celebration' is the definition.
(carnival is a kind of celebration)
'boy embracing ivan excitedly' is the wordplay.
'boy' becomes 'carl' (**).
'embracing' is an insertion indicator.
'excitedly' indicates anagramming the letters.
'ivan' with letters rearranged gives 'niva'.
'carl' enclosing 'niva' is 'CARNIVAL'.
'in' is the link.
(Other definitions for carnival that I've seen before include "Time of public revelry" , "Mardi Gras, for example" , "festive occasion" , "Fiesta" , "Meddle" .)