Pleased with simplicity (4)
I believe the answer is:
ease
'simplicity' is the definition.
(synonyms)
'pleased with' is the wordplay.
'with' indicates the answer is hidden within the clue.
'EASE' is hidden in the letters of 'pleased'.
(Other definitions for ease that I've seen before include "Poise or leisure" , "Freedom from discomfort or anxiety" , "Comfort or freedom from difficulty" , "Comfort; simplicity" , "Facilitate; repose" .)