Flowers might flower around spring and summer, primarily (3,7)
I believe the answer is:
may blossom
'flowers' is the definition.
(I've seen this before)
'might flower around spring and summer primarily' is the wordplay.
I cannot really understand how this works, but
'might' could be 'may' (I've seen this before) and 'may' is located in the answer.
'flower' could be 'blossom' (synonyms) and 'blossom' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
(Another definition for may blossom that I've seen is " Hawthorn flowers".)