Learner in good Scottish organisation (5)
I believe the answer is:
guild
'organisation' is the definition.
(I know that guild is a type of association)
'learner in good scottish' is the wordplay.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'in' is an insertion indicator.
'good scottish' becomes 'guid' (Scottish version of 'good').
'l' inserted within 'guid' is 'GUILD'.
(Other definitions for guild that I've seen before include "corporation" , "Crafstmen's association" , "Trade union" , "The Townswomen's - -" , "Alliance" .)