Nilote worked with hard, stone tool (7)
I believe the answer is:
neolith
'stone tool' is the definition.
(I've seen this before)
'nilote worked with hard' is the wordplay.
'worked with' indicates an anagram.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'nilote' is an anagram of 'neolit'.
'neolit'+'h'='NEOLITH'
(Other definitions for neolith that I've seen before include "Prehistoric stone tool - hotline (anag)" , "Ancient stone implement" , "maybe used at Stonehenge?" , "Stone Age artefact" , "Old stone tool" .)