Beginning to develop a smell after end of afternoon (7)
I believe the answer is:
nascent
'beginning to develop' is the definition.
(I've seen this before)
'a smell after end of afternoon' is the wordplay.
'smell' becomes 'scent' (scent is a kind of smell**).
'after' is a charade indicator (letters next to each other).
'end of' indicates one should take the final letters.
The last letter of 'afternoon' is 'n'.
'a'+'scent'='ascent'
'ascent' put after 'n' is 'NASCENT'.
(Other definitions for nascent that I've seen before include "Freshly generated" , "being coined" , "Coming into existence" , "Just beginning existence" , "Budding early" .)