Crossword Genius

Material English teacher understood (8,2)

Ross

I believe the answer is:

cottoned on

'understood' is the definition.
(to cotton on to something is to understand it)

'material english teacher' is the wordplay.
'material' becomes 'cotton' (cotton is a kind of material).
'english' becomes 'E' (abbreviation as in OED).
'teacher' becomes 'don' (don can mean an academic - especially at Oxbridge).
'cotton'+'e'+'don'='COTTONED ON'

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