Answer:
I am a protector. I sit on a bridge. One person can see right through me while others wonder what I hide.
My first is a heir; My second's a snare; my whole is the offspring of fancy; which I sent out of play upon Valentine's day As a token of love to my Nancy.
Iām white; perfect for cutting & grinding. For most animals I am a useful tool.
When the clock has no angle, I will own yesterday, tomorrow and tonight. What am I?
I am clean when Iām black dirty when Iām white.
It is something you make after you've weighed your options.