Poet begins your education about Tennyson's sonnets (5)
I believe the answer is:
yeats
'poet' is the definition.
(I know that Yeats is a poet)
'begins your education about tennyson's sonnets' is the wordplay.
'begins' says to take the initial letters.
The first letters of 'your education about tennyson sonnets' is 'YEATS'.
(Other definitions for yeats that I've seen before include "Irish poet, 1923 Nobel Prize winner" , "W. B. -- , Irish poet/dramatist" , "William Butler .. . . ., Nobel-winning poet" , "Poet William Butler or painter Jack B" , "W B . . . . ., great Irish poet" .)