Pass through negotiator (2-7)
I believe the answer is:
go-between
'negotiator' is the definition.
(I know that go-between is a type of negotiator)
'pass through' is the wordplay.
'pass' becomes 'go' (synonyms).
'through' becomes 'between' (I can't explain this - if you can you should give a lot more credence to this answer).
'go'+'between'='GO-BETWEEN'
Can you help me to learn more?
(Other definitions for go-between that I've seen before include "One who acts as messenger or negotiator" , "Runner" , "Intermediary" .)