Warm, new filling cooked with the last bits of special pastry (8)
I believe the answer is:
friendly
'warm' is the definition.
(associated in meaning)
'new filling cooked with the last bits of special pastry' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'filling' is an insertion indicator.
'cooked with' becomes 'fried' (frying is a kind of cooking. I am not sure about the 'with' bit.).
'the last bits of' suggests the final letters.
The final letters of 'special pastry' are 'ly'.
'n' inserted within 'fried' is 'friend'.
'friend'+'ly'='FRIENDLY'
Can you help me to learn more?
(Other definitions for friendly that I've seen before include "prepared to talk to fellow passengers?" , "such a society" , "Amiable" , "Affable" , "Amicable, favourably disposed" .)