By concealing the real trouble - having blurred vision (6)
I believe the answer is:
bleary
'having blurred vision' is the definition.
(I've seen this in another clue)
'by concealing the real trouble' is the wordplay.
'concealing' means one lot of letters goes inside another.
'trouble' indicates an anagram.
'real' with letters rearranged gives 'lear'.
'by' going around 'lear' is 'BLEARY'.
(Other definitions for bleary that I've seen before include "Like the unfocused vision" , "Eyes like this are dull from exhaustion" , "Blurred" , "lacking focused vision" , "Smudged, indistinct" .)