Two cardinals about to do some packing (4)
I believe the answer is:
stow
'do some packing' is the definition.
(I've seen this in another clue)
'two cardinals about to' is the wordplay.
'two cardinals' can mean two substitutions for 'cardinal'.
'cardinal' becomes 'S' (South, a cardinal direction).
'cardinal' becomes 'w' (West, a cardinal direction).
'about' says to put letters next to each other.
'w' put after 'to' is 'tow'.
's'+'tow'='STOW'
(Other definitions for stow that I've seen before include "Pack away cargo" , "Fill by packing tightly" , "Deposit" , "Put away for storage" , "Pack tightly" .)