ENTERTAINED (enter + stain - s + ed)
Annoying neighbor flips rumpus room by North Belgium (3, 8)
NED FLANDERS (den backwards + Flanders)
Little bird telling stories to the pigs? (5,6)
Not 100% sure of this one. Is it STOOL PIGEON?
Yup, that’s right.
Cool 
In that case:
Jittery online coke dealer first watches cartoons here (11)
NICKLEODEON (online + coke + d)
Butcher and demon chose this viewing option (2, 6)
Butcher and demon chose this viewing option (2, 6)
ON DEMAND (anagram)
+++++
Famous lion tamer distributed colanders (9)
Not quite.
pollution = TAINT
So we have probe = ENTER
endless pollution = TAINT - T = TAIN
So when you put ENTER against TAIN you get ENTERTAIN
finalized by editor (ED)
Ah, but “Stain” pulls from the other end. 
Androcles (anagram of COLANDERS)
+++++
Mangled insole? That’s gonna leave a mark. (6)
LESION (anagram of insole)
Weep at the transformation: ionized aerated particles of vegetable matter yield lachromosity! (5)
Weep at the transformation: ionized aerated particles of vegetable matter yield lachromosity! (5)
ONION (container)
+++++
Brad mentioned a terrible way to lose your money in the Sahara (3, 5, 6)
Actually I guess this is more accurate:
ONION (container)
+++++
Brad mentioned a terrible way to lose your money in the Sahara (3-5, 6)
Las Vegas Casino?
Las Vegas Casino?
No. Playing off of “ONION”
Is “Casino” on the right track?
Is “Casino” on the right track?
The word “casino” is not in the answer but you are in the neighborhood.
/forehead slap
ONE-ARMED BANDIT (anagram of “Brad mentioned a”)
I thought it was anagram at first, but I couldn’t think of what it would unscramble to. “Sahara” kept making me think of desert, until I googled and found that it’s a casino name. I was also ready to post LAS VEGAS NEVADA before you put in the dash. Good one @Biotop!
Bumstead’s boss babbles (7)
DITHERS (double meaning)
+++++
Chocolate bar of no height examined bomb site. (6)
Oh, all right.
Chocolate bar with no height examined bomb site. (still 6)