TIP OF THE TONGUE

I'm not found on the tip of the tongue,
But I'm usually quite close by;
Add a letter and you will see
That I'll soon take wing and fly.

What am I?

HINT:
Tongue is a homograph.

Answer (in verse):

Hang your head if you missed the clue,
But this riddle is about a shoe. 
A shoe has a tongue that is covered in lace, 
With an AGLET at its tip
To keep frayed ends in place.

Add an E and you will see,
As well as an eagle does,
That the EAGLET will be
Above you and me
As soon as it loses its fuzz.