Drive to discourage race on M1 (13)
I believe the answer is:
determination
'drive' is the definition.
(thesaurus)
'discourage race on m1' is the wordplay.
'discourage' becomes 'deter' (synonyms).
'race' becomes 'nation' (both can mean a national or ethnic group).
'on' says to put letters next to each other.
'md' becomes 'mi' (resembles Md).
'nation' after 'mi' is 'mination'.
'deter'+'mination'='DETERMINATION'
'to' acts as a link.
(Other definitions for determination that I've seen before include "Perseverance" , "Firm resolve" , "Firmness of purpose" , "Decision process" , "Resoluteness" .)