I can't find it online but in Home Depot I found a little bottle of "hard to kill weed killer" for clover & a few others. Green bottle maybe 12 oz size. It was concentrate so had to use a hose end sprayer for it. So far it looks like the clover is all dying around here!

Clover is a perennial that is stoloniferous and reproduces from seed. Spray it post emergently with any 3 way herbicide (MCPP, 2,4D, and dicamba) late spring and early fall.Dimension nor Halts controls clover from seed. Gallery (Isoxben) does,apply late summer/early fall. You can also apply Gallery with Dimension in spring if needed.

Anything with the active ingredient Triclopyr at 8%. In the big-box stores, that will be Ortho Clover, Chickweed and Oxalis Killer ("CCO"). Do not panic and think it isn't working if nothing happens for 10-12 days -- Triclopyr is a slower kill than products like Weed-B-Gon. Repeat the treatment at Day 14.

+1 for Andy.

Yep +1 for Andy that's what the product I used was called, I think I got an old labeled bottle but the clover is all nearly invisible now. I don't little bits of it here and there but it was becoming a clover patch in one area!

+1 Andy, CCO will take care of it without high and unnecessary costs. Pre-M for clover is a waste of money considering how easy it is to get rid of with CCO.

Not sure if you have a lot of clover or not, but if you do, your soil is telling you something. Have you got a soil test lately?

Just in case the OP goes agoogling. There is no relation between clover and low nitrogen.