Save son caught parking on edge (6)
I believe the answer is:
scrimp
'save' is the definition.
(scrimping is a kind of saving)
'son caught parking on edge' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'caught' becomes 'c' (cricket abbreviation).
'parking' becomes 'p' (abbreviation on road signs).
'on' is a charade indicator (letters next to each other).
'edge' becomes 'rim' (rim is a kind of edge).
'p' put after 'rim' is 'rimp'.
's'+'c'+'rimp'='SCRIMP'
(Other definitions for scrimp that I've seen before include "To pinch pennies" , "Be thrifty and parsimonious" , "Treat stingily" , "Be niggardly" , "Economise, be thrifty" .)