Decorate new road layout first (5)
I believe the answer is:
adorn
'decorate' is the definition.
(synonyms)
'new road layout first' is the wordplay.
'new' becomes 'n' (abbreviation as in New Testament NT).
'layout' indicates an anagram (an alternative layout of the letters).
'first' says to put letters next to each other.
'road' anagrammed gives 'ador'.
'n' after 'ador' is 'ADORN'.
(Other definitions for adorn that I've seen before include "dress" , "Festoon" , "Deck" , "Attire" , "get dressed!" .)