Can I knit with dk wool on 7 mm needles the pattern says double strand but was going to try just one strand , will this work
You can mnit in any size needle you want but a thicker needle will guve a more open fabric. You might love it, or you might not. Personal preference.
If it’s for a pattern where the size matters it’s not likely to turn out the right size or drape by working with one thread instead of 2. In any case a gauge swatch is recommended before starting a project where size matters such as a sweater. If you’re making a scarf you might not mind it being a different size and drape.
If you knit up a swatch with the single thread, about 20cm Square and wash and dry I you will find out if you like the fabric and will be able to ok out the gauge for altering sizing.