Sources of rum in Oman? Just any wine! (5)
I believe the answer is:
rioja
'wine' is the definition.
(Rioja is an example)
'sources of rum in oman? just any' is the wordplay.
'sources of' suggests taking the first letters.
The initial letters of 'rum in oman just any' is 'RIOJA'.
(Other definitions for rioja that I've seen before include "North Spanish wine" , "Open space (ancient Greek)" , "Spanish red wine" , "wine region" , "Wine from northern Spain" .)