Pool perhaps by the empty cell (6)
I believe the answer is:
gamete
'cell' is the definition.
(gamete is a kind of cell)
'pool perhaps by the empty' is the wordplay.
'pool perhaps' becomes 'game' (pool is a kind of game).
'by' is a charade indicator (letters next to each other).
'empty' suggests removing the centre.
'the' with its centre taken out is 'te'.
'game'+'te'='GAMETE'
(Other definitions for gamete that I've seen before include "Reproductive unit" , "An egg or sperm cell" , "Egg-cell" , "Egg- or sperm-cell" , "Germ cell in reproduction" .)