To just fail to link up means nothing (3)
I believe the answer is:
nil
'nothing' is the definition.
(eg nil is zero in football)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for nil that I've seen before include "Non-existent" , "Score of nought" , "There's nothing left" , "Nothing, zilch" , "Latin zero" .)