Understandable (8)
I believe the answer is:
coherent
'understandable' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for coherent that I've seen before include "making sense" , "Orderly, logical, consistent" , "Holding together as a whole" , "Sticking together" , "Logical and lucid" .)