The bar on the left, always (5)
I believe the answer is:
lever
'the bar' is the definition.
(lever is a kind of bar)
'on the left always' is the wordplay.
'on' is a charade indicator (letters next to each other).
'the left' becomes 'l' (common abbreviation).
'always' becomes 'ever' ('ever' can be a synonym of 'always').
'l' next to 'ever' is 'LEVER'.
(Other definitions for lever that I've seen before include "exert force, in a way" , "Bar for prising something" , "Pivoting bar, handle" , "Lifting bar pivoted on a fulcrum" , "Machine operator" .)