Mechanical saw bishop lifted (6)
I believe the answer is:
bottom
'mechanical' is the definition.
(a 'mechanical' from A Midsummer Night's Dream)
'saw bishop lifted' is the wordplay.
'saw' becomes 'motto' (saw can mean a proverb or saying).
'bishop' becomes 'B' (chess abbreviation).
'lifted' shows that the letters should be reversed in order (going up in down clue).
'motto'+'b'='mottob'
'mottob' written backwards gives 'BOTTOM'.
(Other definitions for bottom that I've seen before include "A Midsummer-Night's Dream character" , "far end" , "dry bed" , "Behind" , "Quark's flavour" .)