Growth that may be dated (4,4)
I believe the answer is:
palm tree
'growth that may be dated' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'growth that may' is the wordplay.
'growth' becomes 'palm' (I am not sure about this - if you are sure you should believe this answer much more).
'that may' becomes 'tree' (I've seen this before).
'palm'+'tree'='PALM-TREE'
Can you help me to learn more?
(Other definitions for palm tree that I've seen before include "plant to yield oil" , "Its fruit may be dates or coconuts" , "One may supply dates" , "Tropical plant with unbranched trunk" , "Coconut plant" .)