Help one gamble (4)
I believe the answer is:
abet
'help' is the definition.
(thesaurus)
'one gamble' is the wordplay.
'one' becomes 'a'.
'gamble' becomes 'bet' (betting is a kind of gambling**).
'a'+'bet'='ABET'
(Other definitions for abet that I've seen before include "Aid and assist" , "Assist criminally" , "Aid (a criminal)" , "Encourage (wrongdoing)" , "Aid - connive with" .)