Watchword of many a German? (5)
I believe the answer is:
motto
'watchword' is the definition.
(thesaurus)
'many a german?' is the wordplay.
'many' becomes 'm' (**).
'a german?' becomes 'otto' (I've seen this before).
'm'+'otto'='MOTTO'
'of' acts as a link.
(Other definitions for motto that I've seen before include "Saw" , "Phrase on, eg, family coat of arms" , "device" , "Phrase in a Christmas cracker" , "Recurring musical phrase" .)