Plumper son's game (8)

I believe the answer is:

rounders

'game' is the definition.
(rounders is a kind of game)

'plumper son's' is the wordplay.
'plumper' becomes 'rounder' (round can mean plump).
'rounder'+'s'='ROUNDERS'

(Other definitions for rounders that I've seen before include "Local form of American baseball" , "Baseball for kids?" , "Bat-and-ball game" , "Game resembling baseball" , "Game like baseball" .)

I've seen this clue in The Telegraph.

Want a hint initially instead of a full solution? Install my app