clean ‧ ly /ˈkliːnli/ BrE AmE adverb
[ Word Family: noun : ↑ cleaner , ↑ cleaning , ↑ cleanliness , ↑ clean , ↑ cleanser ; verb : ↑ clean , ↑ cleanse ; adverb : ↑ clean , ↑ cleanly ; adjective : ↑ clean ≠ ↑ unclean ]
1 . quickly and smoothly with a single movement:
The branch snapped cleanly in two.
2 . without producing dirt, pollution etc:
a fuel that burns cleanly without loss of power