I see Leo currently has "at it - daran", but that sounds a bit odd to me as the only translation of the word on its own. Would make a lot more sense to me to just leave out any translation of the word in isolation and let people see the examples of what it means within phrases. Maybe add (auch: dadran) in brackets to the other 'daran' examples, such as "jmdn. daran hindern, etw.Akk. zu tun" etc?
Especially as, in isolation, 'at it' means this in BE:
engaged in some activity, typically a reprehensible one:
the council is at it again, wanting to turn another green patch into a carparkhttp://oxforddictionaries.com/definition/engl...
Oh, same in AE:
: doing some activity
▪ I didn't expect her to have started working yet, but she was already (hard) at it when I arrived. [=she was already working (hard) when I arrived] ▪ My neighbors are always arguing, and they were at it again last night. [=they were arguing again last night] ▪ Since we're cleaning the kitchen, we should wash the floor while we're at it. [=we should wash the floor when we clean the kitchen] ▪ “I'm going to the store to buy a newspaper.” “While you're at it, could you get some milk?” http://www.learnersdictionary.com/search/at%20it