Point to organist's control in bar (5)
I believe the answer is:
estop
'bar' is the definition.
(I've seen this in another clue)
'point to organist's control in' is the wordplay.
'point' becomes 'E' (compass point).
'organist's control' becomes 'sp' (I can't explain this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'to' going inside 'sp' is 'stop'.
'e'+'stop'='ESTOP'
Can you help me to learn more?
(Other definitions for estop that I've seen before include "Legally check" , "Legally hinder removal" , "Bar, for a lawyer" , "Preclude certain evidence (at law) - bar (archaic)" , "Hinder, preclude (law)" .)