Recorder mishandled test case (8)
I believe the answer is:
cassette
'recorder' is the definition.
(cassette recorder is a kind of recorder)
'mishandled test case' is the wordplay.
'mishandled' indicates an anagram.
'test'+'case'='testcase'
'testcase' anagrammed gives 'CASSETTE'.
(Other definitions for cassette that I've seen before include "It may contain film" , "Container that holds a magnetic tape" , "Recorder would accommodate this" , "Music player" , "Source of music" .)