Braid (5)
(Other definitions for tress that I've seen before include "is a bit of a shock" , "Braid of hair" , "Long lock or plait of hair" , "Bit of hair" , "Long piece of hair" .)
'braid' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for plait that I've seen before include "Interwoven length of hair" , "Braided pigtail" , "Interlaced length of hair" , "Braided hair" , "Weave; queue" .)