In essay, absorbing conclusion (6)
I believe the answer is:
trendy
'in' is the definition.
('in' can mean trendy or fashionable)
'essay absorbing conclusion' is the wordplay.
'essay' becomes 'try' (synonyms).
'absorbing' indicates putting letters inside.
'conclusion' becomes 'end' (something's conclusion is its end).
'try' placed around 'end' is 'TRENDY'.
(Other definitions for trendy that I've seen before include "all the rage" , "Informally in the latest fashion" , "following fashion" , "Cool" , "Consciously fashionable" .)