Chimney, pillar with less attractive shape? (7)
I believe the answer is:
lumpier
'with less attractive shape?' is the definition.
(lumpy can mean with a more unattractive shape)
'chimney pillar' is the wordplay.
'chimney' becomes 'lum' (I've seen this in other clues).
'pillar' becomes 'pier' (I've seen this in another clue).
'lum'+'pier'='LUMPIER'
(Other definitions for lumpier that I've seen before include "more uneven" , "Having more bulges" , "With more large bits" .)