The Irish love fashionable cereals (5)
I believe the answer is:
grain
'cereals' is the definition.
(I've seen this before)
'the irish love fashionable' is the wordplay.
'the irish love' becomes 'gra' (I've seen this in another clue).
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'gra'+'in'='GRAIN'
(Other definitions for grain that I've seen before include "Character" , "Small piece of sand" , "Small hard particle, of rice perhaps" , "little salty bit" , "Eg, wheat" .)