Sidle on in elegantly, circling like a cat (7)
I believe the answer is:
leonine
'like a cat' is the definition.
(I've seen this before)
'sidle on in elegantly circling' is the wordplay.
'circling' says the answer is hidden in the clue (the answer is circled or surrounded by the clue).
'LEONINE' is hidden in the letters of 'sidle on in elegantly'.
(Other definitions for leonine that I've seen before include "Imposing like a lion" , "Resembling a big cat" , "Resembling a lion" , "Papal" , "Description of pride" .)