Connected by wire out in the field (2,3,4)
I believe the answer is:
on the line
'connected' is the definition.
I know nothing about this answer so I can't judge whether this works.
'by wire out in the field' is the wordplay.
'by' says to put letters next to each other.
'wire out in' becomes 'on' (I can't explain this - if you can you should give a lot more credence to this answer).
'field' becomes 'line' (both can refer to an industry or area of expertise).
'on' next to 'the' is 'onthe'.
'onthe'+'line'='ON THE LINE'
Can you help me to learn more?
(Other definitions for on the line that I've seen before include "At serious risk" , "At risk - or speaking on telephone" , "Using the phone" , "Caller may be" , "when one is at risk" .)