In denouement, seek to entertain (6)
I believe the answer is:
trendy
'in' is the definition.
('in' can mean trendy or fashionable)
'denouement seek to entertain' is the wordplay.
'denouement' becomes 'end' (the end or conclusion of a story).
'seek' becomes 'try' (synonyms).
'to entertain' means one lot of letters goes inside another.
'end' inserted inside 'try' is 'TRENDY'.
(Other definitions for trendy that I've seen before include "Chic (colloq.)" , "In fashion, of popular style" , "Consciously fashionable" , "Cool" , "Informally, following the fashions" .)