Connected everything that is disconnected at first (6)
I believe the answer is:
allied
'connected' is the definition.
(allied can mean connected or associated)
'everything that is disconnected at first' is the wordplay.
'everything' becomes 'all' (all things).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'at first' suggests taking the first letters.
The initial letter of 'disconnected' is 'd'.
'all'+'ie'+'d'='ALLIED'
(Other definitions for allied that I've seen before include "Joined together for a purpose" , "Joined in friendship, treaty, etc" , "United through treaty" , "Joined to, combined with" , "Joined by treaty or agreement" .)