Concert in timeless African port going ahead (6)
I believe the answer is:
unison
'concert' is the definition.
(thesaurus)
'timeless african port going ahead' is the wordplay.
'timeless african port going' becomes 'unis' (I can't justify this - if you can you should believe this answer much more).
'ahead' becomes 'on' ('on' can be a synonym of 'ahead').
'unis'+'on'='UNISON'
'in' is the link.
Can you help me to learn more?
(Other definitions for unison that I've seen before include "Close agreement" , "Voices in complete agreement" , "Accord" , "with regard to the pitch" , "In agreement - like sound of choir" .)