Bloke outside can upset restraining device (7)
I believe the answer is:
manacle
'restraining device' is the definition.
(manacles restrain someone's hands or feet)
'bloke outside can upset' is the wordplay.
'bloke' becomes 'male' (bloke can mean a man).
'outside' indicates putting letters inside.
'upset' is an anagram indicator.
'can' is an anagram of 'nac'.
'male' placed around 'nac' is 'MANACLE'.
(Other definitions for manacle that I've seen before include "Hand/ankle restraint" , "Metal shackle" , "restricting at the cuff?" , "Shackle on the wrist" , "Handcuff" .)