Quick drink before road trip starts (5)
I believe the answer is:
alert
'quick' is the definition.
(thesaurus)
'drink before road trip starts' is the wordplay.
'drink' becomes 'ale' (ale is a kind of drink**).
'before' says to put letters next to each other.
'starts' indicates taking the first letters.
The first letters of 'road trip' is 'rt'.
'ale'+'rt'='ALERT'
(Other definitions for alert that I've seen before include "Watchful and bright" , "Signal danger" , "Put on guard, warn" , "Lively" , "'Attentive, watchful (5)'" .)