They may relieve tension, but be sad to do this? (5,5)

I believe the answer is:
worry beads
'they' is the definition.
Both the answer and definition are plural nouns.
Maybe there's an association between them I don't understand?
'relieve tension but be sad to do this?' is the wordplay.
I cannot quite see how this works, but
'be' is within the answer.
an anagram of 'sad' is 'ads' which is within the answer.
The remaining letters 'worry' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'may' acts as a link.
Can you help me to learn more?
(Other definitions for worry beads that I've seen before include "String of them for fiddling with" , "These may help, at a click of the fingers" .)
