They indicate approval of bedding equipment (5)
I believe the answer is:
ticks
'they' is the definition.
Both the definition and answer are plural nouns.
Maybe you can see an association between them that I don't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for ticks that I've seen before include "Parasitic arachnids" , "Makes noise like old clock" , "Marks correct" , "They suck from warm-blooded animals" , "Parasites" .)