It promises fruitfulness, perhaps, with expansion just around the corner (5)
I believe the answer is:
bloom
This clue could be a double definition.
'it promises fruitfulness perhaps with expansion just' is the first definition.
The definition suggests a singular noun which matches the answer.
'the corner' is the second definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'around' is the link.
Can you help me to learn more?
(Other definitions for bloom that I've seen before include "Blossom, flower" , "Flush" , "(Come into) flower" , "Produce flowers" , "look good" .)