Indicate, designate (6)
I believe the answer is:
denote
This clue is a double definition.
'indicate' is the first definition.
(I've seen this before)
'designate' is the second definition.
(denoting is a kind of designating)
(Other definitions for denote that I've seen before include "Stand as symbol for" , "Indicate, signify" , "Indicate, be a sign of" , "Need to (anag) - indicate" , "Be an indication of" .)