Get me a modified germ cell (6)
I believe the answer is:
gamete
'germ cell' is the definition.
(gamete is a kind of germ cell)
'get me a modified' is the wordplay.
'modified' indicates an anagram.
'get'+'me'+'a'='getmea'
'getmea' anagrammed gives 'GAMETE'.
(Other definitions for gamete that I've seen before include "something seedy?" , "An egg or sperm cell" , "Egg- or sperm-cell" , "Male or female germ cell" , "Cell which unites with another in reproduction to form a zygote" .)