For the trip in, about one day (4)
I believe the answer is:
ride
'for the trip' is the definition.
(thesaurus)
'in about one day' is the wordplay.
'in' means one lot of letters goes inside another.
'about' becomes 're' (regarding**).
'one' becomes 'i' (Roman numeral).
'day' becomes 'd'.
'i'+'d'='id'
're' going around 'id' is 'RIDE'.
(Other definitions for ride that I've seen before include "Travel on (a bicycle)" , "Travel, on horseback, say" , "Travel on the back of animal" , "Jaunt" , "Travel in or be carried on" .)