I prevent mom's tipsy advances (12)
I believe the answer is:
improvements
'advances' is the definition.
('improvement' can be a synonym of 'advance')
'i prevent mom's tipsy' is the wordplay.
'tipsy' indicates an anagram.
'prevent'+'moms'='preventmoms'
'preventmoms' with letters rearranged gives 'mprovements'.
'i'+'mprovements'='IMPROVEMENTS'
(Other definitions for improvements that I've seen before include "Reforms" , "Changes for the better" , "advances" , "better progress" .)