Flask in bag right at the bottom (10)
I believe the answer is:
nethermost
'the bottom' is the definition.
(I've seen this before)
'flask in bag right' is the wordplay.
'flask' becomes 'thermos' (thermos is a kind of flask).
'in' is an insertion indicator.
'bag right' becomes 'net' (I've seen this in other clues. I am not sure about the 'right' bit.).
'thermos' going within 'net' is 'NETHERMOST'.
'at' acts as a link.
Can you help me to learn more?
(Other definitions for nethermost that I've seen before include "at the bottom of the pile" , "located in lowest position" .)