Forgotten in Nice, a dilapidated rental (8)
I believe the answer is:
unlearnt
'forgotten' is the definition.
The answer and definition can be both related to thinking as well as being past participle verbs.
Maybe you can see a link between them that I can't see?
'nice a dilapidated rental' is the wordplay.
'nice' becomes 'un' (I can't explain this - if you can you should believe this answer much more).
'a dilapidated' is an anagram indicator.
'rental' with letters rearranged gives 'learnt'.
'un'+'learnt'='UNLEARNT'
'in' acts as a link.
Can you help me to learn more?
(Another definition for unlearnt that I've seen is " Disregarded".)