Acceleration going down in journey to bring top place? (5)
I believe the answer is:
ridge
'top place?' is the definition.
(eg a mountain ridge)
'acceleration going down in journey' is the wordplay.
'acceleration going down' becomes 'G' (gravity).
'in' is an insertion indicator.
'journey' becomes 'ride' (ride is a kind of journey).
'g' inserted inside 'ride' is 'RIDGE'.
'to bring' is the link.
(Other definitions for ridge that I've seen before include "High land" , "Bump between furrows" , "there's a lot of pressure in it" , "Long, narrow hilltop" , "Raised edge" .)