Reproductive cell of a plucky little teen (6)
I believe the answer is:
gamete
'reproductive cell' is the definition.
(gamete is a kind of reproductive cell)
'a plucky little teen' is the wordplay.
'a plucky' becomes 'game' (both can mean enthusiastic or willing).
'little teen' becomes 'te' (I can't justify this - if you can you should give a lot more credence to this answer).
'game'+'te'='GAMETE'
'of' is the link.
Can you help me to learn more?
(Other definitions for gamete that I've seen before include "Egg- or sperm-cell" , "Egg-cell" , "something seedy?" , "Reproductive cell" , "Cell which unites with another in reproduction to form a zygote" .)