Guaranteed to take off last chunky skirt (8)
I believe the answer is:
surround
'skirt' is the definition.
(skirt can mean to go around or surround)
'guaranteed to take off last chunky' is the wordplay.
'guaranteed' becomes 'sure' (I've seen this in other clues).
'to take off last' means to remove the last letter.
'chunky' becomes 'round'.
'sure' with its last letter taken away is 'sur'.
'sur'+'round'='SURROUND'
(Other definitions for surround that I've seen before include "Encompass" , "Ring" , "Encircle, fence in" .)