One of three given journey permit (7)
I believe the answer is:
triplet
'one of three' is the definition.
(I've seen this before)
'journey permit' is the wordplay.
'journey' becomes 'trip' (trip is a kind of journey).
'permit' becomes 'let' ('let' can be a synonym of 'permit').
'trip'+'let'='TRIPLET'
'given' is the link.
(Other definitions for triplet that I've seen before include "One of several arriving together" , "sibling?" , "One of a small group" , "One of three children" , "Group of three equal notes" .)