Picnic in light wind (6)
I believe the answer is:
breeze
I believe this is a double definition.
'picnic' is the first definition.
(I know that picnic can be written as breeze)
'light wind' is the second definition.
(a breeze is a wind)
'in' acts as a link.
(Other definitions for breeze that I've seen before include "breath of fresh air" , "get the wind up" , "Walk in the park" , "Simple task" , "The building block is light" .)