Person cool in tight corset (6)
I believe the answer is:
bodice
'tight corset' is the definition.
'person cool' is the wordplay.
'person' becomes 'bod' (bod can informally mean a person or body).
'cool' becomes 'ice' (icing is a kind of cooling).
'bod'+'ice'='BODICE'
'in' acts as a link.
(Other definitions for bodice that I've seen before include "Top of a dress above the waist" , "Sexually explicit historical novel" , "Upper half of dress" , "Stays" , "tight-fitting costume?" .)