In the end, do your best to ring (6)
I believe the answer is:
trendy
'in' is the definition.
('in' can mean trendy or fashionable)
'end do your best to ring' is the wordplay.
'do your best' becomes 'try'.
'to ring' means one lot of letters goes inside another.
'end' placed into 'try' is 'TRENDY'.
'the' acts as a link.
(Other definitions for trendy that I've seen before include "In fashion, of popular style" , "Voguish" , "Up-to-date with the latest fad" , "following latest convention" , "Less sensible; a dye plant" .)