Attack of giggles possibly showing Bottom up in middle of June, for example? (9)
I believe the answer is:
onslaught
'attack' is the definition.
(an onslaught is an attack)
I don't understand how the rest of the clue works.
(Other definitions for onslaught that I've seen before include "Assault" , "Hunt goals (anag) - offensive" , "Barrage" , "offensive action" , "Aggressive action" .)