Island tour extremely popular — I join parent (8)
I believe the answer is:
trinidad
'island' is the definition.
(Trinidad is an example)
'tour extremely popular i join parent' is the wordplay.
'extremely' suggests removing the centre.
'popular' becomes 'in'.
'join' is a charade indicator (letters next to each other).
'parent' becomes 'dad' (dad is a kind of parent**).
'tour' with its centre taken out is 'tr'.
'tr'+'in'+'i'+'dad'='TRINIDAD'
(Other definitions for trinidad that I've seen before include "English-speaking island off Venezuela" , "Caribbean island" , "West Indies island" , "... [WI ISLAND]" , "Port of Spain island" .)