I don’t know you primarily process refuse (4,2)
I believe the answer is:
pass up
'refuse' is the definition.
(to pass up on something is to refuse or reject it)
'i don't know you primarily process' is the wordplay.
'i don't know' becomes 'pass' ('pass' is said to skip a question).
'you' becomes 'u' (commonly used in online communication).
'primarily' says to take the initial letters.
The initial letter of 'process' is 'p'.
'pass'+'u'+'p'='PASS UP'
(Other definitions for pass up that I've seen before include "Miss" , "Showing neglect" , "Fail to take advantage of" , "Refrain from taking an opportunity" , "col?" .)