Jewelled item found in Croatia rarely (5)
I believe the answer is:
tiara
'jewelled item' is the definition.
'in croatia rarely' is the wordplay.
'in' indicates a hidden word.
'TIARA' can be found hidden inside 'croatia rarely'.
'found' acts as a link.
(Other definitions for tiara that I've seen before include "Ornamental head band" , "Jewelled head wear" , "Pope's triple-tiered crown" , "pope may have been topped by one" , "Ornamental crescent-shaped headdress or Pope's diadem" .)