Comfort lecturer in bar (5)
I believe the answer is:
salve
'comfort' is the definition.
(I've seen this before)
'lecturer in bar' is the wordplay.
'lecturer' becomes 'l' (abbreviation for lecturer).
'in' means one lot of letters goes inside another.
'bar' becomes 'save' (both can mean 'except').
'l' put within 'save' is 'SALVE'.
(Other definitions for salve that I've seen before include "Welcome" , "Unguent" , "comfort" , "Save - ointment" , "Ointment; soothe" .)