Formerly in agreement with herb given orally (2,3,4)
I believe the answer is:
at one time
'formerly' is the definition.
(I've seen this before)
'in agreement with herb given orally' is the wordplay.
'in agreement with' becomes 'atone' (I've seen this before).
'herb' becomes 'thyme' (thyme is a kind of herb).
'given orally' indicates a 'sounds like' (homophone) clue.
'thyme' sounds like 'time'.
'atone'+'time'='AT ONE TIME'
(Other definitions for at one time that I've seen before include "in the past" , "Taking place simultaneously" , "in concert" , "together" , "Formerly" .)