Poet composing sonnet about New York (8)
I believe the answer is:
tennyson
'poet' is the definition.
(Alfred, Lord Tennyson)
'composing sonnet about new york' is the wordplay.
'composing' is an anagram indicator.
'about' indicates putting letters inside.
'new york' becomes 'ny'.
'sonnet' anagrammed gives 'tenson'.
'tenson' going around 'ny' is 'TENNYSON'.
(Other definitions for tennyson that I've seen before include "linesman" , "The Charge of the Light Brigade poet" , "English Victorian poet" , "C19 Poet Laureate" , "Poet Laureate from 1850 to 1892" .)