Audio device blasted trees round (6)
I believe the answer is:
stereo
'audio device' is the definition.
'blasted trees round' is the wordplay.
'blasted' indicates anagramming the letters.
'round' becomes 'o' (round can mean a round object).
'trees' is an anagram of 'stere'.
'stere'+'o'='STEREO'
(Other definitions for stereo that I've seen before include "Three dimensional sound effect" , "Twin-channel sound" , "Music system with two speakers" , "Tape recorder" , "System that gives a three-dimensional sound" .)