Bond returning nothing to king (4)
I believe the answer is:
link
'bond' is the definition.
(I know that bond is a more specific form of the action attach)
'returning nothing to king' is the wordplay.
'returning' shows that the letters should be reversed in order.
'nothing' becomes 'nil' (eg nil is zero in football).
'to king' becomes 'K' (chess abbreviation).
'nil' back-to-front is 'lin'.
'lin'+'k'='LINK'
(Other definitions for link that I've seen before include "Item of mail" , "Chain component" , "One ring or loop of a chain" , "Join; loop in a chain" , "Tie-up" .)