Devour teachers' union who erode this (3,4)
I believe the answer is:
eat into
'devour' is the definition.
The definition and answer can be both related to consumption as well as being verbs in their base form.
Perhaps they are linked in a way I don't understand?
'teachers' union who erode this' is the wordplay.
I cannot quite understand how this works, but
'erode' could be 'eat' (I've seen this in another clue) and 'eat' is present in the answer.
The remaining letters 'into' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for eat into that I've seen before include "start wearing out" , "Corrode (something)" , "Etch" , "run down" , "Consume (resources)" .)