Solution for hygienist opening laundry (9)
I believe the answer is:
mouthwash
'solution for hygienist' is the definition.
(solution a hygienist might use)
'opening laundry' is the wordplay.
'opening' becomes 'mouth' (mouth is a kind of opening).
'laundry' becomes 'wash' (synonyms).
'mouth'+'wash'='MOUTHWASH'
(Other definitions for mouthwash that I've seen before include "rubbish" , "Oral rinse" , "Liquid breath freshener" , "Medicated solution used for gargling" , "Gargle" .)