Wait and finally get washbasin (5)
I believe the answer is:
bidet
'washbasin' is the definition.
(thesaurus)
'wait and finally get' is the wordplay.
'wait' becomes 'bide' (I've seen this before).
'and' is a charade indicator (letters next to each other).
'finally' suggests the final letters.
The final letter of 'get' is 't'.
'bide'+'t'='BIDET'
(Other definitions for bidet that I've seen before include "Bathroom fitment" , "Debit (anag)" , "Cleaning vessel for privates" , "Stay behind" , "Washing facility" .)