Islander's bar joined by regulars from club (5)
I believe the answer is:
cuban
'islander's' is the definition.
(I've seen this before)
'bar joined by regulars from club' is the wordplay.
I cannot really understand how this works, but
'bar' could be 'ban' (bar can mean to ban or prohibit) and 'ban' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for cuban that I've seen before include "Kind of high quality cigar" , "Relating to Castro's isle" , "Havana native" , "sort of heel" , "islander" .)