A hit with poem that is fashionable (1,2,4)
I believe the answer is:
a la mode
'is fashionable' is the definition.
(a la mode can mean trendy or fashionable)
'a hit with poem' is the wordplay.
'hit' becomes 'lam' (to 'lam' means to hit hard).
'with' is a charade indicator (letters next to each other).
'poem' becomes 'ode' (ode is a kind of poem).
'a'+'lam'+'ode'='A-LA-MODE'
'that' is the link.
(Other definitions for a la mode that I've seen before include "In fashion (French)" , "Do a meal in French style (1, 2, 4)" , "In fashion - served with ice cream" , "stewed with veg?" , "Fashionable in France" .)