Kind to carry son in downward journey (7)
I believe the answer is:
descent
'downward journey' is the definition.
(I've seen this before)
'kind to carry son in' is the wordplay.
'kind' becomes 'decent' (I've seen this before).
'to carry son' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'decent' placed around 's' is 'DESCENT'.
Can you help me to learn more?
(Other definitions for descent that I've seen before include "Slope leading from top" , "Ancestry - downward move" , "Decline" , "Pedigree" , "Downward path" .)