Biology classes sure began badly (9)
I believe the answer is:
subgenera
'biology classes' is the definition.
(I've seen this before)
'sure began badly' is the wordplay.
'badly' indicates an anagram (letters in the wrong order).
'sure'+'began'='surebegan'
'surebegan' anagrammed gives 'SUBGENERA'.
(Other definitions for subgenera that I've seen before include "taxonomic groups" , "Biology classes" , "Small groups" , "Biological groups" .)