Prevent entry of mischievous Peke, newly released (4,3)
I believe the answer is:
keep out
'prevent entry' is the definition.
'keep out' can be an answer for 'prevent' (keeping out is a kind of preventing). I am not certain of the 'entry' bit.
'mischievous peke newly released' is the wordplay.
I cannot really see how this works, but
an anagram of 'peke' is 'keep' which is present in the answer.
'released' could be 'out' (eg out of prison) and 'out' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for keep out that I've seen before include "bar" , "Don't trespass" , "warning note to trespassers?" , "Stay clear" , "notice to trespassers?" .)