Lively friend protected by a new identity (8)
I believe the answer is:
animated
'lively' is the definition.
(synonyms)
'friend protected by a new identity' is the wordplay.
'friend' becomes 'mate' (mate is a kind of friend).
'protected by' is an insertion indicator (inserted letters are held or protected).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'identity' becomes 'id' (abbreviation).
'a'+'n'+'id'='anid'
'mate' placed into 'anid' is 'ANIMATED'.
(Other definitions for animated that I've seen before include "full of spirit" , "Vivacious in diamante" , "Mandate I got to be lively" , "Interesting and lively - as a cartoon film is" , "Lively - like cartoon films" .)