Still sorting out three sevens divided by fifty? (12)
I believe the answer is:
nevertheless
'still' is the definition.
(synonyms)
'sorting out three sevens divided by fifty?' is the wordplay.
'sorting out' is an anagram indicator.
'divided by' indicates putting letters inside.
'fifty?' becomes 'l' (roman numeral).
'three'+'sevens'='threesevens'
'threesevens' with letters rearranged gives 'nevertheess'.
'nevertheess' placed around 'l' is 'NEVERTHELESS'.
(Other definitions for nevertheless that I've seen before include "However" , "anyhow" , "In spite of everything" , "Notwithstanding" , "But always" .)