Rinse out sap (5)
I believe the answer is:
resin
'sap' is the definition.
(I've seen this before)
'rinse out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'rinse' is an anagram of 'RESIN'.
(Other definitions for resin that I've seen before include "varnish, perhaps" , "component of varnish" , "Viscous fluid from tree sap" , "Unprocessed pine secretion" , "Sticky substance exuded by pine trees" .)