Resolve to put off race crossing major road (13)
I believe the answer is:
determination
'resolve' is the definition.
(I know that determination is a type of resolve)
'put off race crossing major road' is the wordplay.
'put off' becomes 'deter' (both can mean to discourage).
'race' becomes 'nation' (both can mean a national or ethnic group).
'crossing' indicates putting letters inside (to cross can mean to go over or around).
'major road' becomes 'MI' (resembles Mn, English motorway).
'deter'+'nation'='deternation'
'deternation' enclosing 'mi' is 'DETERMINATION'.
'to' acts as a link.
(Other definitions for determination that I've seen before include "Resolution" , "legal decision" , "Firmness of purpose" , "Firm resolve" , "Decision process" .)