Soldier left inside joined drill (6)
I believe the answer is:
gimlet
'drill' is the definition.
(I know that gimlet is a type of drill)
'soldier left inside joined' is the wordplay.
I cannot really understand how this works, but
'soldier' could be 'gi' (term for US soldier) and 'gi' is found in the answer.
'left' could be 'l' (common abbreviation) and 'l' is located in the answer.
'joined' could be 'met' (meeting is a kind of joining) and 'met' is located in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for gimlet that I've seen before include "Hand tool for boring holes" , "Boring tool; US cocktail" , "Hole borer" , "Something for boring; cocktail" , "Gin and lime juice cocktail - boring tool" .)