Missing half of claw tool (4)
I believe the answer is:
awol
'missing' is the definition.
(military abbreviation for absent without leave)
'half of claw tool' is the wordplay.
I cannot quite understand how this works, but
'of' could be 'o' and 'o' is located in the answer.
'tool' could be 'awl' (awl is a kind of tool) and 'awl' is present in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for awol that I've seen before include "unaccounted for" , "Absent without permission, in short" , "Absent without leave (abbr.)" , "'Absent without permission, initially (4)'" , "Not present when supposed to be" .)