I’m welcomed by a security organisation, being notedly lively (7)
I believe the answer is:
animato
'being notedly lively' is the definition.
(musical term - as in musical notes)
'i'm welcomed by a security organisation' is the wordplay.
'welcomed by' indicates putting letters inside (letters welcomed inside).
'security organisation' becomes 'NATO' (North Atlantic Treaty Organisation).
'a'+'nato'='anato'
'im' going within 'anato' is 'ANIMATO'.
(Other definitions for animato that I've seen before include "Performed musically in lively manner" , "Fire" , "Orchestra's lively" .)