Crook hit Leo? Old stone tool? (6)
I believe the answer is:
eolith
'stone tool?' is the definition.
(I've seen this before)
'crook hit leo?' is the wordplay.
'crook' indicates an anagram (a crooked or broken form of the letters).
'hit'+'leo'='hitleo'
'hitleo' with letters rearranged gives 'EOLITH'.
'old' acts as a link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for eolith that I've seen before include "Old stone implement" , "Flint" , "stone tool" , "Elvis Presley song" , "Very early stone implement to be found in the oil" .)