Nice grid, my era too

Good gridding. I got one wrong; adding just one of the letters rather than three, also spells words.

@E.L. - thought the same initially, just adding a "t" to each word (if that was the letter you were thinking of!) but wasn't sure about Devo(t), seemingly only an archaic spelling of devout... still, like yourself got it wrong...7/10 coz I can't spell ;)

easy

Fluked the "-ted" category!

certainly not one for a mongoloid

I like the "cold" group

Can also add just ‘t’ to those words..

Good but tricky one, so many band names to throw you.

You can add 'ting' to those words too...

T also works as an answer.

Good one, but I also just missed out because of the adding letters one. I thought, just a t, but that's debatable. Thanks.