Ten numbers recalled in poem (6)
I believe the answer is:
sonnet
'poem' is the definition.
(type of poem)
'ten numbers recalled' is the wordplay.
'numbers' becomes 'nos' ('no' is an abbreviation for number).
'recalled' shows that the letters should be reversed in order (to recall can mean to bring something back).
'ten'+'nos'='tennos'
'tennos' back-to-front is 'SONNET'.
'in' acts as a link.
(Other definitions for sonnet that I've seen before include "Poem of 14 lines - Shakespeare wrote lots" , "Poetic fourteen-liner" , "14-line verse" , "Sent on the verse form" , "Shakespearean poem" .)