Rum, maybe from Italy, son left half-finished (4)
I believe the answer is:
isle
'rum maybe' is the definition.
(as in the Isle of Rum in the Inner Hebrides)
'italy son left half-finished' is the wordplay.
'italy' becomes 'i'.
'son' becomes 's' (genealogical abbreviation for son).
'half-finished' indicates taking half.
'left' cut in half is 'le'.
'i'+'s'+'le'='ISLE'
'from' acts as a link.
(Other definitions for isle that I've seen before include "Man, Wight, etc" , "This is sceptred!" , "isolated spot" , "Eg, eyot or inch" , "Prince Edward perhaps" .)