Unusual street oven (7)
I believe the answer is:
strange
'unusual' is the definition.
(I know that unusual can be written as strange)
'street oven' is the wordplay.
'street' becomes 'st' (abbreviation).
'oven' becomes 'range' (I've seen this in another clue).
'st'+'range'='STRANGE'
(Other definitions for strange that I've seen before include "Odd kind of garnets" , "Different" , "Abnormal" , "Odd or unknown" , "Funny" .)