Easy to understand one covering the eyes touring capitals (5)
I believe the answer is:
lucid
'easy to understand' is the definition.
(I've seen this before)
'one covering the eyes touring capitals' is the wordplay.
'one covering' becomes 'blue' (blue is a kind of covering).
'the eyes' indicates the central letters (I've seen 'eye' mean this (eye can mean the centre of something)).
'touring capitals' becomes 'cid' (I am not sure about this - if you are sure you should believe this answer much more).
The middle of 'blue' is 'lu'.
'lu'+'cid'='LUCID'
(Other definitions for lucid that I've seen before include "Crystal clear" , "Clear; making sense" , "Easily understood; sane" , "Quite clear" , "Clear, easily understood" .)