It may appear in bars of musical work as prelude to movement (5)
I believe the answer is:
optic
'it may appear in bars' is the definition.
(device for preparing drinks)
'musical work as prelude to movement' is the wordplay.
'musical work' becomes 'op' (abbreviation for opus).
'as prelude to' says to put letters next to each other.
'movement' becomes 'tic' (I have seen 'Nervous movement' mean 'tic' so perhaps 'movement' could also mean 'tic').
'op'+'tic'='OPTIC'
'of' is the link.
(Other definitions for optic that I've seen before include "Spirits measurer" , "Pub measure" , "Of sight or the eye" , "Of the eye - drinks dispenser" , "Pub drinks dispenser" .)