Custom in remarkable Capri, etc. (8)
I believe the answer is:
practice
'custom' is the definition.
(I've seen this before)
'remarkable capri etc' is the wordplay.
'remarkable' is an anagram indicator.
'capri'+'etc'='caprietc'
'caprietc' is an anagram of 'PRACTICE'.
'in' is the link.
(Other definitions for practice that I've seen before include "The exercise of a profession" , "Team of doctors" , "training" , "Habit - procedure" , "It makes perfect, 'tis said" .)