Fireworks spread widely (4)
I believe the answer is:
rife
'spread widely' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I can't see?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for rife that I've seen before include "Very common or frequently occurring" , "Abounding" , "is everywhere" , "Overabundant" , "raging" .)