Another word for opportunity which begins with 'S' is scope.
softening
Scrap.
Steam
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.
One word would be "prince". Add an -s and you have the plural - "princes". Add another -s and you have "princess", a word in singular form.
synopsis
Side-Street
Substitute.
softening
sojourn
spousal
Sort or Savor
stole
source spring square
My thesaurus lists stick or stab. The noun "lance" is related to spear.
an alliteation is a word in a sentence which have the same beginning word example.. she sings sweetly.. (s,s,s)
sop