Verse has singular beat unknown by leading academic (6)
I believe the answer is:
stanza
'verse' is the definition.
(a stanza is a verse of a poem)
'singular beat unknown by leading academic' is the wordplay.
'singular' becomes 's' (abbreviation sometimes used in dictionaries).
'beat' becomes 'tan' (I've seen this before).
'unknown by leading academic' becomes 'za' (I can't justify this - if you can you should believe this answer much more).
's'+'tan'+'za'='STANZA'
'has' acts as a link.
Can you help me to learn more?
(Other definitions for stanza that I've seen before include "Group of lines of verse" , "Fixed number of lines of verse" , "Section of poem" , "Chunk of poetry" , "Lines of poetry forming a pattern" .)