Type of pasta mostly found in lively Siena, a feature of Italy (9)
I believe the answer is:
apennines
'a feature of italy' is the definition.
I can't judge whether this definition defines the answer.
'type of pasta mostly found in lively siena' is the wordplay.
'type of pasta' becomes 'penne' (I've seen this in another clue).
'mostly' means to remove the last letter (most but not all of the word).
'found in' is an insertion indicator.
'lively' is an anagram indicator (letters get livened up or moved around).
'penne' with its last letter taken off is 'penn'.
'siena' anagrammed gives 'aines'.
'penn' put inside 'aines' is 'APENNINES'.
Can you help me to learn more?
(Other definitions for apennines that I've seen before include "Italian mountain chain" , "Mountain range in central Italy" , "Italian mountains" , "Great mountain range in Italy (9)" , "Italian mountain range" .)