Curious new difficulty upset poet (8)
I believe the answer is:
tennyson
'poet' is the definition.
(Alfred, Lord Tennyson)
'curious new difficulty upset' is the wordplay.
'curious' becomes 'nosy' (similar in meaning).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'difficulty' becomes 'net' (net can mean a difficulty).
'upset' is a reversal indicator.
'nosy'+'n'+'net'='nosynnet'
'nosynnet' backwards is 'TENNYSON'.
(Other definitions for tennyson that I've seen before include "writer" , "Alfred Lord . . . . . . . . great poet of 'The Lady of Shalott'" , "Alfred Lord . . . . . . . . great English poet" , "British poet" , "Poet who wrote The Lady of Shalott" .)