Cord; series (6)
I believe the answer is:
string
This clue is a double definition.
'cord' is the first definition.
(I know that string is a type of cord)
'series' is the second definition.
(sequence of similar items or events)
(Other definitions for string that I've seen before include "Cord, twine" , "train" , "Thin length of cord etc" , "It's difficult to say how long a piece of it is" , "light cord" .)