Stalk group that could become anything (4,4)
I believe the answer is:
stem cell
'stalk group that could become anything' is the definition.
The definition suggests a singular noun which matches the answer.
'stalk group' is the wordplay.
'stalk' becomes 'stem' (synonyms).
'group' becomes 'cell' (I can't justify this - if you can you should believe this answer much more).
'stem'+'cell'='STEM CELL'
Can you help me to learn more?
(Other definitions for stem cell that I've seen before include "Versatile building block of life" , "Undifferentiated unit of life" , "body-builder" , "biological germ" , "Undifferentiated functional unit in an organism" .)