Slack engineers fail to make connection (6)
I believe the answer is:
remiss
'slack engineers' is the definition.
'remiss' can be an answer for 'slack' (thesaurus). I'm not certain of the 'engineers' bit.
'fail to make connection' is the wordplay.
'fail' becomes 'miss' (missing is a kind of failing).
'to' says to put letters next to each other (I've seen this in other clues).
'make connection' becomes 're' (I can't explain this - if you can you should believe this answer much more).
'miss' put after 're' is 'REMISS'.
Can you help me to learn more?
(Other definitions for remiss that I've seen before include "delinquent" , "Negligent, lax" , "Negligent in performing duties" , "Negligent in performance of duty" , "Lacking care to duty" .)