Thus I invite competition for a group of flowers (6)
I believe the answer is:
raceme
'group of flowers' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'thus i invite competition' is the wordplay.
I cannot really see how this works, but
'i' could be 'me' and 'me' is found in the answer.
'competition' could be 'race' (race is a kind of competition) and 'race' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'for a' is the link.
Can you help me to learn more?
(Other definitions for raceme that I've seen before include "Long cluster of flowers along the main stem" , "Elongated cluster of flowers along a main stem" , "Cluster of flowers along a central stem" , "Flowers evenly spaced along central stem" , "Flower cluster (botany)" .)