On a trip, passed in jet (6,3)
I believe the answer is:
spaced out
'on a trip' is the definition.
(I've seen this before)
'passed in jet' is the wordplay.
'passed' becomes 'aced' (acing is a kind of passing).
'in' indicates putting letters inside.
'jet' becomes 'spout' (I've seen this in another clue).
'aced' put into 'spout' is 'SPACED OUT'.
(Other definitions for spaced out that I've seen before include "affected by drugs" , "Placed well apart - unaware of one's surroundings" , "Disorientated through drug use" , "in a dazed state" , "High on drugs" .)