Think about body shape (6)
I believe the answer is:
figure
I believe this clue is a double definition.
'think' is the first definition.
(I know that figure is a more specific form of the action reason)
'body shape' is the second definition.
(I've seen this before)
'about' is the link.
(Other definitions for figure that I've seen before include "Symbol representing a number" , "The written symbol of a number" , "form" , "Shape; amount of money" , "Symbol, numeral" .)