This is a strophe from a song:
"Well, she stands all around me her hands slowly sifting the sunshine
all the laughter that linger down deep 'neath her smilin' is free
Well, it spins and it twirls like a hummingbird lost in the morning
and caresses the south wind and silently sails to the sea"
But I'm not sure how the down affects the idea of linger. Is it necessary for the deep?
Could I rewrite the sentence this way:
All the laughter that linger (down) under her smiling is free
In standard English: All the laughter that lingers down deep beneath her smile is free.
Country singers sometimes leave off the 's' on plurals as a purely stylistic thing. Those who actually speak with that deep of an accent have a different enough grammar that it's a slightly different dialect. "Smilin'" instead of smile is a similar effect. I don't know this dialect enough to explain the internal logic it follows.
Edit: sorry, I almost forgot: "down deep" is a unit that's much more widespread. "Down" just intensifies "deep", which is intensifying "beneath".
