Occasionally questions German taking drugs (5)
I believe the answer is:
using
'taking drugs' is the definition.
(I've seen this before)
'occasionally questions german' is the wordplay.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
'german' becomes 'g' (abbreviation).
The alternate letters of 'questions' are 'usin'.
'usin'+'g'='USING'
(Other definitions for using that I've seen before include "Employing" , "Exploiting for one's own advantage" , "Putting to a particular purpose" , "addiction" , "Utilising" .)