Burden women's rowing crew? (6)
I believe the answer is:
weight
'burden' is the definition.
(I know that burden can be written as weight)
'women's rowing crew?' is the wordplay.
'women' becomes 'w' (standard abbreviation).
'rowing crew?' becomes 'eight' (crew of eight rowers).
'w'+'eight'='WEIGHT'
(Other definitions for weight that I've seen before include "Heavy load - preponderance" , "Gravitational pull" , "Trouble" , "The property of heaviness, measure of mass" , "Significance" .)