Sort of block an easy task (6)
I believe the answer is:
breeze
I believe this is a double definition.
'sort of block' is the first definition.
(as in breezeblocks)
'an easy task' is the second definition.
(something easy is said to be a breeze)
(Other definitions for breeze that I've seen before include "picnic" , "easy task to move?" , "Simple task" , "Doddle - light wind" , "Light cooling wind" .)