enigmatic puzzle - Iambic Pentameter

_{Part of the Fortnightly Topic Challenge #35: Restricted Title 1}

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The type of party that may startle you

Defiant age range, kids no longer sweet

Irrat'nal number formed when over two

For adult and buffoon, it can succeed

A word my browser, Chrome, has near undo

Had worn a buckle that is for the street

A reddish laser must process to view

The place that you would find a thesmothete

It means brutal, harsh, or caustic too

In terms of verse like this, it's seven feet

8 5 7 3 6 10 3 6 6 10

----->

6 (=) 4

----->

2 8

----->

10 4

Answer

Previous answers and comments have outlined all the answers to the clues already, plus one in chat. Please go and give the other answers some +1s for their work. I'll list the clued words here again, but without the extra space for all the lines:

SURPRISE, TEENS, RADICAL, -ERY, SECURE, SEATBELTED, DVD, ATHENS, SAVAGE, HEPTAMETER

Now to interpret the numbers below the poem.

8 5 7 3 6 10 3 6 6 10  

Enumerations (word lengths) for the above answers, to help confirm when an answer was right. If the rest of the numbers are also enumerations, then these answers lead to a six-letter word and a four-letter word that we should equate.

6 (=) 4

Taking the first letters of the ten clues words in order, we get STRESS (=) DASH. Somehow, the idea that stress=dash should lead to a two-letter word and an eight-letter word.

2 8

Since this is a puzzle about poetic metre and syllables, Deusovi suggested in chat the idea of scansion, where stressed syllables in words are represented with lines (dashes, or rather macrons) and unstressed syllables are represented with a shorter rounder symbol.
This is a hint to reuse our ten clued words, but instead of looking at first letters, now look at stressed/unstressed syllable patterns. With stress=dash and unstress=dot, each word gives a letter in Morse code. (For example, heptameter is ".-.."; in the provided link, the apostrophe indicates a stressed syllable.)
The Morse code letters spell out AT DIAGONAL.

10 4

Finally, we need to use a diagonal somehow to extract a ten-letter word and a four-letter word. In this case, we're not using the clued words again; we're going back to the original clues.
Ten lines of ten syllables each; taking the diagonal in this case means taking the first syllable of the first line, then the second syllable of the second line, and so on.
THE, -FI-, 'NAL, AND, -SER
THAT, PROs-, THE[s]-, -TIC, FEET
(I think the sixth line may be off by a syllable and should be IS.)

Final answer for this poetic puzzle:

The final answer is PROSTHETIC FEET.