Decorate road, terribly new (5)
I believe the answer is:
adorn
'decorate' is the definition.
(synonyms)
'road terribly new' is the wordplay.
'terribly' indicates anagramming the letters.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'road' anagrammed gives 'ador'.
'ador'+'n'='ADORN'
(Other definitions for adorn that I've seen before include "Embellish, decorate" , "Deck" , "Make more attractive" , "Bedeck" , "get dressed!" .)