Fashions in first of modern poems (5)
I believe the answer is:
modes
'fashions' is the definition.
('mode' can be a synonym of 'fashion')
'first of modern poems' is the wordplay.
'first of' says to take the initial letters.
'poems' becomes 'odes' (ode is a kind of poem).
The first letter of 'modern' is 'm'.
'm'+'odes'='MODES'
'in' acts as a link.
(Other definitions for modes that I've seen before include "Styles (in clothes, etc)" , "Ways - manners" , "Styles of domes" , "Fashions" .)