What Ofsted does this month is to cover heads of primary English course (7)
I believe the answer is:
inspect
'what ofsted does' is the definition.
(Ofsted inspects UK schools)
'this month is to cover heads of primary english course' is the wordplay.
'this month' becomes 'inst' (letter-writing abbreviation for this month).
'is to cover' means one lot of letters goes inside another.
'heads of' says to take the initial letters.
The initial letters of 'primary english course' is 'pec'.
'inst' placed around 'pec' is 'INSPECT'.
(Other definitions for inspect that I've seen before include "Scrutinize, audit" , "Examine officially" , "Carefully examine" , "Scan" , "vet" .)