Circles having lengths within bounds (7)
I believe the answer is:
lollops
'bounds' is the definition.
(to lollop is to gallop or bound around)
'circles having lengths within' is the wordplay.
'circles' becomes 'loops' (looping is a kind of circling).
'having lengths' becomes 'll' (I can't explain this - if you can you should give a lot more credence to this answer).
'within' is an insertion indicator.
'loops' going around 'll' is 'LOLLOPS'.
(Other definitions for lollops that I've seen before include "Bounds clumsily" , "Lopes" , "Lounges" .)