Top poetry composed as an exemplar (9)
I believe the answer is:
prototype
'an exemplar' is the definition.
(thesaurus)
'top poetry composed' is the wordplay.
'composed' indicates an anagram.
'top'+'poetry'='toppoetry'
'toppoetry' is an anagram of 'PROTOTYPE'.
'as' is the link.
(Other definitions for prototype that I've seen before include "Typical example" , "exemplar" , "Original model - top poetry (anag)" , "Preliminary version from which other forms may be developed" , "First version (of a device) built for development" .)