Securely wrap son before walk like this (7)
I believe the answer is:
swaddle
'securely wrap' is the definition.
(as in swaddling a child)
'son before walk like this' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'before' says to put letters next to each other.
'walk like this' becomes 'waddle' (waddling is a way of walking).
's'+'waddle'='SWADDLE'
(Other definitions for swaddle that I've seen before include "Bind tight with clothes" , "Wrap with bandages" , "Wrap up well" , "Wind bandages round" , "Bandage - wrap (baby) tightly" .)