A piece of cake? It may need a bit more than that! (6)
I believe the answer is:
picnic
'a piece of cake?' is the definition.
(both can mean something easy)
I cannot understand how the remainder of the clue works.
(Other definitions for picnic that I've seen before include "external courses?" , "Informal excursion with meal in open air" , "Meal eaten outside" , "Alfresco meal" , "outdoor eating" .)