Nothing brought up by king to make connection (4)
I believe the answer is:
link
'connection' is the definition.
(I know that link is a type of linkage)
'nothing brought up by king' is the wordplay.
'nothing' becomes 'nil' (eg nil is zero in football).
'brought up' shows that the letters should be reversed in order (in a down clue, letters go up).
'by' says to put letters next to each other.
'king' becomes 'K' (chess abbreviation).
'nil' written backwards gives 'lin'.
'lin'+'k'='LINK'
'to make' acts as a link.
(Other definitions for link that I've seen before include "Relationship; loop in a chain" , "Connexion" , "Join together" , "One ring or loop of a chain" , "A chain is as strong as its weakest one" .)