As drawn, they vary in length (6)
I believe the answer is:
straws
'as drawn they' is the definition.
The definition suggests a plural noun which matches the answer.
'vary in length' is the wordplay.
I cannot really understand how this works, but
'length' could be 'r' (r is a kind of length) and 'r' is located in the answer.
The remaining letters 'staws' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for straws that I've seen before include "Hollow tubes for drinking" , "Lots" , "are drawn thusto drink!" , "Dried stalks used as fodder or bedding" , "Thin tubes to suck up liquid" .)