Simply (6)
'simply' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for easily that I've seen before include "without a hitch?" , "With little difficulty" , "Without difficulty or effort" , "Without much difficulty" , "Very probably" .)
'simply' is the definition.
(I know that simply can be written as merely)
This is all the clue.
(Other definitions for merely that I've seen before include "'Only, and nothing more (6)'" , "Simply - only" , "Just one" .)