Sicilian eminence wants petunia in prime locations (4)
I believe the answer is:
etna
'sicilian eminence' is the definition.
(volcano on Sicily)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for etna that I've seen before include "Impressive mount" , "smoker in Sicily" , "From a dangerous height" , "Highest peak in Italy south of the Alps" , "Neat (anag)" .)