Im tall, educated, English and unrivalled
I believe the answer is:
alltime
'unrivalled' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'im tall educated english' is the wordplay.
I cannot quite see how this works, but
'im' is within the answer.
an anagram of 'tall' is 'allt' which is within the answer.
'english' could be 'e' (abbreviation) and 'e' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Another definition for alltime that I've seen is " Unsurpassed".)