Wrap up little son needing sort of walk (7)
I believe the answer is:
swaddle
'wrap up' is the definition.
(I've seen this before)
'little son needing sort of walk' is the wordplay.
'little son' becomes 's' (abbreviation for son).
'needing' means one lot of letters go next to another.
'sort of walk' becomes 'waddle'.
's'+'waddle'='SWADDLE'
(Other definitions for swaddle that I've seen before include "Fully cover" , "Bind tight with clothes" , "Wrap up well" , "Wind bandages round" , "Wrap with bandages" .)