Bold claim about drained sinks (5)
I believe the answer is:
sassy
'bold' is the definition.
(I've seen this before)
'claim about drained sinks' is the wordplay.
'claim' becomes 'say' (I've seen this in another clue).
'about' indicates putting letters inside.
'drained' says to hollow out the word (remove centre letters).
'sinks' with its centre removed is 'ss'.
'say' going around 'ss' is 'SASSY'.
(Other definitions for sassy that I've seen before include "(In US) saucy" , "Cheeky American" , "Pert" , "Impertinent (US colloq.)" , "Cheeky (US colloq.)" .)