Unusual way, developing anger (7)
I believe the answer is:
strange
'unusual' is the definition.
(similar in meaning)
'way developing anger' is the wordplay.
'way' becomes 'st' (abbreviation for street).
'developing' indicates anagramming the letters (letters developed into a new form).
'anger' with letters rearranged gives 'range'.
'st'+'range'='STRANGE'
(Other definitions for strange that I've seen before include "Odd - rum" , "- - Fruit (song)" , "Singular" , "Weird, eerie" , "Funny" .)