Mount perhaps and start on a journey (3,3)
I believe the answer is:
set off
This clue could be a double definition.
'mount perhaps' is the first definition.
'set off' can be an answer for 'mount' (thesaurus). I am unsure of the 'perhaps' bit.
'start on a journey' is the second definition.
(I've seen this before)
'and' acts as a link.
Can you help me to learn more?
(Other definitions for set off that I've seen before include "Begin journey or cause to ignite" , "Begin journey or explode bomb" , "Begin journey or detonate bomb" , "show to advantage" , "Explode; start journey" .)