Easily understandable (5)
I believe the answer is:
lucid
'easily understandable' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lucid that I've seen before include "Clear, easily understandable" , "Clear, easily understood" , "Coherent" , "Clear, sane" , "Easy to understand, clearly expressed" .)