Dress cleavage is gripping sight (7)
I believe the answer is:
raiment
'dress' is the definition.
(I know that dress can be written as raiment)
'cleavage is gripping sight' is the wordplay.
'cleavage' becomes 'rent' (both can mean a tear or split in something).
'is gripping' indicates putting letters inside (inserted letters are gripped).
'sight' becomes 'aim' (I've seen this in another clue).
'rent' enclosing 'aim' is 'RAIMENT'.
(Other definitions for raiment that I've seen before include "Clothing (literary)" , "Wear" , "Fancy clothes seen on minaret" , "Garb" , "clothing for poets" .)