Supervise poetry in Old English (7)
I believe the answer is:
oversee
'supervise' is the definition.
(I know that supervise can be written as oversee)
'poetry in old english' is the wordplay.
'poetry' becomes 'verse' (synonyms).
'in' means one lot of letters goes inside another.
'old english' becomes 'OE'.
'verse' placed into 'oe' is 'OVERSEE'.
(Other definitions for oversee that I've seen before include "Keep an eye on like foreman" , "Supervise, control" , "guide" , "risk eyestrain?" , "Keep a check on" .)