Clear cover around university key (5)
I believe the answer is:
lucid
'clear' is the definition.
(similar in meaning)
'cover around university key' is the wordplay.
'cover' becomes 'lid' (lid is a kind of cover).
'around' indicates putting letters inside.
'university key' becomes 'uc' (I can't explain this - if you can you should give a lot more credence to this answer).
'lid' placed around 'uc' is 'LUCID'.
Can you help me to learn more?
(Other definitions for lucid that I've seen before include "Able to think clearly" , "Thinking clearly" , "Bright; sane" , "Compos mentis" , "Readily understood" .)