Telling falsehoods — some only in German (5)
I believe the answer is:
lying
'telling falsehoods' is the definition.
(I've seen this before)
'some only in german' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'LYING' is hidden in the letters of 'only in german'.
(Other definitions for lying that I've seen before include "Prostrate -- prone" , "Anything but upright" , "Telling untruths" , "Telling falsehoods" , "Saying what is 23" .)