Shorten "Send off to get into shape" (8)
I believe the answer is:
condense
'shorten' is the definition.
(condensing is a kind of shortening)
'send off to get into shape' is the wordplay.
'off' indicates anagramming the letters.
'to get into' is an insertion indicator.
'shape' becomes 'cone' (cone is a kind of shape**).
'send' anagrammed gives 'dens'.
'dens' going inside 'cone' is 'CONDENSE'.
(Other definitions for condense that I've seen before include "Make more concise" , "Reduce volume" , "Turn from gas to liquid" , "Send once (anag.)" , "contract?" .)