Like the yolk in Eggs Benedict (5)
I believe the answer is:
runny
'like the yolk in eggs benedict' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for runny that I've seen before include "Fluid" , "too much liquid" , "Inclined to liquefy, watery" , "Of liquid consistency" , "Like water" .)