Handcuff a salt arrested by setter (7)
I believe the answer is:
manacle
'handcuff' is the definition.
(I know that handcuff can be written as manacle)
'a salt arrested by setter' is the wordplay.
'salt' becomes 'nacl' (NaCl is the chemical formula for sodium chloride).
'arrested by' means one lot of letters goes inside another (inserted letters are held or arrested).
'setter' becomes 'me' (the setter of the clue).
'a'+'nacl'='anacl'
'anacl' placed into 'me' is 'MANACLE'.
(Other definitions for manacle that I've seen before include "item restricting movement" , "Shackle on the wrist" , "Hand/ankle restraint" , "restricting at the cuff?" , "Fetter" .)