Greek and Italian resolution (4)
I believe the answer is:
grit
'resolution' is the definition.
(thesaurus)
'greek and italian' is the wordplay.
'greek' becomes 'gr'.
'and' says to put letters next to each other.
'italian' becomes 'it'.
'gr'+'it'='GRIT'
(Other definitions for grit that I've seen before include "Jock's enormous" , "Fragments to sprinkle on roads" , "Bottle" , "called for on icy roads" , "Determination -- coarse sandstone" .)