Young flower is one containing empty seeds (7)
I believe the answer is:
blossom
'young flower' is the definition.
'blossom' can be an answer for 'flower' (synonyms). I'm not certain of the 'young' bit.
'one containing empty seeds' is the wordplay.
'one' becomes 'bloom' (I can't justify this - if you can you should give a lot more credence to this answer).
'containing' indicates putting letters inside.
'empty' suggests removing the centre.
'seeds' with its centre removed is 'ss'.
'bloom' going around 'ss' is 'BLOSSOM'.
'is' acts as a link.
(Other definitions for blossom that I've seen before include "Wanting to flourish" , "Mass of flowers - mature" , "Mature promisingly" , "May, possibly" , "Bloom" .)