Dispatch son before death (4)
I believe the answer is:
send
'dispatch' is the definition.
(thesaurus)
'son before death' is the wordplay.
'son' becomes 's'.
'before' means one lot of letters go next to another.
'death' becomes 'end' ('end' can be a synonym of 'death').
's'+'end'='SEND'
(Other definitions for send that I've seen before include "Transmit; post" , "Forward" , "Transport" , "Transmit (message)" , "and 2: Advise" .)