Sodium smell coming into existence (7)
I believe the answer is:
nascent
'coming into existence' is the definition.
(I've seen this in another clue)
'sodium smell' is the wordplay.
'sodium' becomes 'NA' (chemical symbol).
'smell' becomes 'scent' (synonyms).
'na'+'scent'='NASCENT'
(Other definitions for nascent that I've seen before include "Developing" , "Starting existence" , "Incipient" , "awakening" , "coming into circulation?" .)