I went through a random word generator until I found a nice one to make a Riley out of:
My Prefix can crunch, wash, or rock.
And can be found prominent, on those who aren't scared.
My Infix grows the prettiest flowers.
But without it, the world will surely be a solemnly bared.
My Suffix strums a sweet melody.
And looks like a fruit, that won't want to be shared.
My whole refuses to be a pessimist.
I tried not to make this too tricky as it's my first post, will give hints as appropriate.
Added an extra line to each section to make it a bit easier (and rhyme).