Find out about unusual sort of radiation (8)
I believe the answer is:
infrared
'sort of radiation' is the definition.
'find out about unusual' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'about' indicates putting letters inside.
'unusual' becomes 'rare' (I've seen this before**).
'find' is an anagram of 'infd'.
'infd' going around 'rare' is 'INFRARED'.
(Other definitions for infrared that I've seen before include "Having longer than visible wavelength" , "Hot objects radiate this" , "Fan drier (anag) - type of radiation" , "With a frequency between the red end of the visible spectrum and microwaves" , "heat" .)