Poem produced by boy on web (6)
I believe the answer is:
sonnet
'poem' is the definition.
(sonnet is a kind of poem)
'boy on web' is the wordplay.
'boy' becomes 'son' ('son' can be a synonym of 'boy'**).
'on' means one lot of letters go next to another.
'web' becomes 'net' ('net' can be a synonym of 'web').
'son'+'net'='SONNET'
'produced by' acts as a link.
(Other definitions for sonnet that I've seen before include "Poem of 14 lines - Shakespeare wrote lots" , "Fourteen-lined verse" , "Fourteen-lined poem" , "Poetic fourteen-liner" , "Fourteen-line poem" .)