The existing entry is correct.
@CJ: >> Allerdings führt der Eintrag time [mus]=das Tempo dazu, daß es so wirkt, als sei es die einzig legitime übersetzung für die musikalsche Verwendung.<<
Quite often, "time" *is* the only correct translation, e.g., "to keep time". So this should not be a problem.
>>Stimmt to keep time= die Zeit anzeigen überhaupt?<<
Right: I think it should be "die Zeit nehmen." See LEO for "timekeeper," which BTW has a redundant plural entry.
>>Wäre to keep time=im Takt bleiben ohne den Verweis aufs Rudern nicht viel sinnvoller?<<
You're absolutely right to drop the rowing. However, I'm wondering about the following distinction:
"to keep time = das Tempo halten," means to *set* a reference, i.e., that's what a drummer or conductor or a click track does.
"to keep in time = den Takt halten," means to acurately follow a *given* reference, i.e., that's what the other musicians do.
Casual use probably doesn't make this distinction but I think it would be precise and correct...