Little negative thing, awful clue (9)
I believe the answer is:
minuscule
'little' is the definition.
(I know that little can be written as minuscule)
'negative thing awful clue' is the wordplay.
'negative thing' becomes 'minus' (pluses and minuses).
'awful' indicates an anagram.
'clue' with letters rearranged gives 'cule'.
'minus'+'cule'='MINUSCULE'
(Other definitions for minuscule that I've seen before include "A lower-case letter" , "Not important" , "Fine" , "not capital" , "Extremely small, tiny" .)