Top's a foot inside container (6)
I believe the answer is:
caftan
'top's' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'a foot inside container' is the wordplay.
'foot' becomes 'ft' (abbreviation).
'inside' is an insertion indicator.
'container' becomes 'can' (can is a kind of container).
'a'+'ft'='aft'
'aft' going inside 'can' is 'CAFTAN'.
Can you help me to learn more?
(Other definitions for caftan that I've seen before include "Loose tunic" , "Long belted male tunic" , "Long coat-like garment worn by men in Middle East" , "Woman's hat" , "Turkish loose garment" .)