Tornado converted into Hummer? (7)
I believe the answer is:
odorant
'hummer?' is the definition.
(something that hums or smells)
'tornado converted' is the wordplay.
'converted' indicates anagramming the letters.
'tornado' with letters rearranged gives 'ODORANT'.
'into' acts as a link.
(Other definitions for odorant that I've seen before include "Tornado (anag)" , "Something emitting a strong smell" , "may create a stink?" , "Aromatic" .)