Each on journey, energetically ambitious (2-5)
I believe the answer is:
go ahead
'ambitious' is the definition.
(I've seen this before)
'each on journey energetically' is the wordplay.
'each' becomes 'ahead' ('a head' can mean 'per person').
'on' means one lot of letters go next to another.
'journey energetically' becomes 'go' (journey means to go or travel. I am not sure about the 'energetically' bit.).
'ahead' put after 'go' is 'GO-AHEAD'.
Can you help me to learn more?
(Other definitions for go ahead that I've seen before include "Up-and-coming -- authorisation" , "Pioneering (green light?)" , "[ENERGETIC]" , "Ambitious" , "dynamic" .)