Cylinder filled with first of Ukraine’s wheat (5)
I believe the answer is:
durum
'wheat' is the definition.
(durum is a kind of wheat)
'cylinder filled with first of ukraine's' is the wordplay.
'cylinder' becomes 'drum' (drum is a kind of cylinder).
'filled with' indicates putting letters inside.
'first of' suggests taking the first letters.
The initial letter of 'ukraine' is 'u'.
'drum' placed around 'u' is 'DURUM'.
(Other definitions for durum that I've seen before include "Type of flour used for pasta" , "Wheat variety" , "Wheat for pasta flour" , "Kind of wheat used to make pasta" , "It makes pasta" .)