German originally devised code, thus settles for no other (4,5)
I believe the answer is:
goes dutch
'settles for no other' is the definition.
(to settle only one's own bill at a restaurant)
'german originally devised code thus' is the wordplay.
'originally' says to take the initial letters.
'devised' is an anagram indicator.
The initial letter of 'german' is 'g'.
'code'+'thus'='codethus'
'codethus' with letters rearranged gives 'oesdutch'.
'g'+'oesdutch'='GOES DUTCH'
(Other definitions for goes dutch that I've seen before include "Shares expenses" , "Pays half" .)