Designates for a particular purpose (8)
I believe the answer is:
earmarks
'designates for a particular purpose' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for earmarks that I've seen before include "Allocates; reserves" , "Characteristic features" , "Designates for a particular purpose" , "Puts distinguishing sign on - begins aurally" , "Sets aside for particular purpose in aural way" .)