Artist detained outside produces trumpet (6)
I believe the answer is:
herald
'trumpet' is the definition.
(thesaurus)
'artist detained outside' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'detained' becomes 'held' (I've seen this in another clue).
'outside' is an insertion indicator.
'ra' put inside 'held' is 'HERALD'.
'produces' is the link.
(Other definitions for herald that I've seen before include "Proclaim the approach of, like old messenger" , "Proclaim the approach of, like archaic messenger" , "Bringer of news" , "Announce, presage" , "Proclaimer" .)