A lot of poetry in Old English, revolutionary to a large extent (4,2)
I believe the answer is:
ever so
'a lot' is the definition.
(thesaurus)
'poetry in old english revolutionary to a large extent' is the wordplay.
I cannot really understand how this works, but
'poetry' could be 'vers' (I've seen this before) and 'vers' is present in the answer.
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is found within the answer.
'english' could be 'e' (abbreviation) and 'e' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for ever so that I've seen before include "Greatly" , "To a very great extent" , "Jolly" , "Extremely" , "Very much" .)