Weak spot in base, some might say (4)
I believe the answer is:
flaw
'weak spot' is the definition.
(I've seen this before)
'base some might say' is the wordplay.
'base' becomes 'floor'.
'some might say' shows a homophone (sound like).
'floor' sounds like 'FLAW'.
'in' is the link.
(Other definitions for flaw that I've seen before include "Imperfection or blemish" , "Mark, blemish" , "Error in theory or plan" , "sudden rush" , "failing" .)