So retirement in Capri turned out to be dull (7)
I believe the answer is:
prosaic
'be dull' is the definition.
(similar in meaning)
'so retirement in capri turned out' is the wordplay.
'so retirement' becomes 'os' (I can't justify this - if you can you should believe this answer much more).
'in' indicates putting letters inside.
'turned out' is an anagram indicator.
'capri' anagrammed gives 'praic'.
'os' going into 'praic' is 'PROSAIC'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for prosaic that I've seen before include "Pedestrian, unimaginative" , "Dull (writing)" , "Poetry would not be so" , "Lacking poetry" , "Hackneyed" .)