Boy new to ET produces poem (6)
I believe the answer is:
sonnet
'poem' is the definition.
(type of poem)
'boy new to et produces' is the wordplay.
'boy' becomes 'son' (synonyms).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'produces' indicates an anagram.
'n' after 'et' is 'etn'.
'etn' anagrammed gives 'net'.
'son'+'net'='SONNET'
(Other definitions for sonnet that I've seen before include "Sent on the verse form" , "Poem of fourteen lines" , "Poetic fourteen-liner" , "14-line poem" , "Poem of 14 lines - Shakespeare wrote lots" .)