They have no power to fly (7)
I believe the answer is:
gliders
'they' is the definition.
Both the definition and answer are plural nouns.
Maybe you can see a link between them that I can't see?
'no power to fly' is the wordplay.
'no power' becomes 'rs' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'to' means one lot of letters go next to another (I've seen this in other clues).
'fly' becomes 'glide' (gliding is a kind of flying).
'rs' put after 'glide' is 'GLIDERS'.
'have' acts as a link.
Can you help me to learn more?
(Another definition for gliders that I've seen is " Flying vehicles without engines".)