Laundry detergent brand (4)
I believe the answer is:
tide
'laundry detergent brand' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tide that I've seen before include "Periodic water movement" , "Powerful surge" , "Movement of seawater" , "Periodic rise and fall of the sea" , "Current, ebb" .)