We engaged in changing style in a pleasant manner (7)
I believe the answer is:
sweetly
'in a pleasant manner' is the definition.
'we engaged in changing style' is the wordplay.
'engaged in' means one lot of letters goes inside another.
'changing' is an anagram indicator.
'style' is an anagram of 'setly'.
'we' going within 'setly' is 'SWEETLY'.
(Other definitions for sweetly that I've seen before include "in a melodious way" , "In an affectionate manner" , "In a kind way" , "Melodiously, kindly" , "Engagingly, gently" .)