Bill allowed nine wayward sons a little sport (5,6)
I believe the answer is:
table tennis
'sport' is the definition.
(I've seen this before)
'bill allowed nine wayward sons a little' is the wordplay.
'bill' becomes 'tab' (a tab is a bill at a bar).
'allowed' becomes 'let' (to let is to allow or permit).
'wayward' indicates an anagram (wayward means out of control or chaotic).
'sons' becomes 'ss' (genealogical abbreviation for son written twice).
'a little' means to remove the last letter (the word is not quite complete).
'ss' with its final letter taken off is 's'.
'nine' anagrammed gives 'enni'.
'tab'+'let'+'enni'+'s'='TABLE-TENNIS'
(Other definitions for table tennis that I've seen before include "Ping pong" , "sport" , "Ping-pong" , "Indoor game" .)