Waves approaching one’s teachers, meeting each (4,3)
I believe the answer is:
head sea
'waves approaching one's' is the definition.
(waves directly ahead of you)
'teachers meeting each' is the wordplay.
'teachers' becomes 'heads' (head or headteacher is a type of teacher).
'meeting' means one lot of letters go next to another.
'each' becomes 'ea'.
'heads'+'ea'='HEAD SEA'
(Other definitions for head sea that I've seen before include "swell of opposition" , "series of waves coming straight at boat" , "Mass of waves approaching front of ship" , "Waves approaching a ship's front" , "obstacle to progress" .)