Son deserting post, as appropriate (4)
I believe the answer is:
take
'appropriate' is the definition.
(I've seen this before)
'son deserting post' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'deserting' is a deletion indicator.
'post' becomes 'stake' (synonyms).
'stake' with 's' removed is 'TAKE'.
'as' is the link.
(Other definitions for take that I've seen before include "Convey; consume" , "Remove, subtract" , "Grab" , "Accept, receive" , "receipts" .)