There are several examples of "s" words that are similar in meaning to "clever," but they do have different connotations associated with them. For instance, snark, which carries a somewhat negative meaning. On the other hand, sharp, has a much more positive meaning.
Smart?
Another word for opportunity which begins with 'S' is scope.
softening
The word beginning is an abstract noun, a word for the start of something.
Scrap.
Steam
Another word for opportunity which begins with 'S' is scope.
synopsis
Sort or Savor
Side-Street
sojourn
spousal
softening
stole
source spring square
"Spear" is another word for "lance" that starts with the letter "s."
smart
The word beginning is an abstract noun, a word for the start of something.