Piece of office equipment tangles up, if misused (6,3)
I believe the answer is:
staple gun
'piece of office equipment' is the definition.
(I know that staple gun is a type of office supply)
'tangles up if misused' is the wordplay.
'if misused' indicates anagramming the letters.
'tangles'+'up'='tanglesup'
'tanglesup' anagrammed gives 'STAPLE GUN'.
(Other definitions for staple gun that I've seen before include "Tool for inserting fasteners" , "One that fires those fixing" .)