With eight sides, round canal got remodelled (9)
I believe the answer is:
octagonal
'with eight sides' is the definition.
(an octagon has eight sides)
'round canal got remodelled' is the wordplay.
'round' becomes 'o' (o is a circular letter).
'remodelled' is an anagram indicator.
'canal'+'got'='canalgot'
'canalgot' anagrammed gives 'ctagonal'.
'o'+'ctagonal'='OCTAGONAL'
(Other definitions for octagonal that I've seen before include "with quite a few sides" , "Having eight straight sides" , "In unusual shape" , "With eight sides and angles" , "with certain sides" .)