Many a German has a maxim (5)
I believe the answer is:
motto
'a maxim' is the definition.
(I've seen this before)
'many a german' is the wordplay.
'many' becomes 'm' (Roman numeral for a thousand).
'a german' becomes 'otto' (common German name).
'm'+'otto'='MOTTO'
'has' acts as a link.
(Other definitions for motto that I've seen before include "Slogan encapsulating self-image" , "Guiding adage" , "Phrase in a Christmas cracker" , "Short sentence expressing an ideal" , "Words often found on coat of arms" .)