Small implement to make low seat (5)
I believe the answer is:
stool
'seat' is the definition.
(stool is a kind of seat)
'small implement to make low' is the wordplay.
I cannot quite understand how this works, but
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is located in the answer.
'implement' could be 'tool' (tool is a kind of implement) and 'tool' is located in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stool that I've seen before include "Backless chair" , "item of furniture here" , "Small seat" , "Armless seat" , "Simple seat" .)