What are some examples from the text that support that Hamlet is, in fact, both morally justified to himself, and clever?

While much has been written of 's delay, it
should be obvious that it is not a simple matter to wander into the throne room one day and kill
the king of Denmark because you think he may have committed a murder for which you have not a
shred of evidence. First,has to satisfy himself that murder has been committed. This he does in
act 5, scene 1. As soon asmentions murder, Hamlet is ready:

Haste me to know't, that I, with wings as swift
As meditation or the thoughts
of love,
May sweep to my revenge.

The ghost
admits that he finds Hamlet "apt." When the ghost has told his tale, Hamlet quickly
makes plans, including a pretense of madness. His intelligence appears in his prescience when he
is communicating to his friends precisely how they should conduct themselves in the face of his
apparent insanity:

As I perchance hereafter shall think
meet
To put an antic disposition on,
That you, at such times seeing me, never
shall,
With arms encumber'd thus, or this headshake,
Or by pronouncing of some
doubtful phrase,
As "Well, well, we know," or "We could, an if we
would,"
Or "If we list to speak," or "There be, an if they
might,"
Or such ambiguous giving out, to note
That you know aught of me:
this not to do,
So grace and mercy at your most need help you, Swear.

We have plenty of witnesses to Hamlet's intellectual brilliance,
not least , who exclaims, when she thinks he is mad,

O,
what a noble mind is here o'erthrown!
The courtier's, soldier's, scholar's, eye,
tongue, sword;
The expectancy and rose of the fair state,
The glass of fashion
and the mould of form,
The observed of all observers, quite, quite down!

However, act 5, scene 1, also shows a level of cunning and subtlety
in planning which is evident in Hamlet's manipulation of the play The Murder of
Gonzago. His moral justification for avenging his father is never in doubt, though he
does have to justify to himself his failure to take revenge as quickly as he thinks he should.
The most convincing of these justifications is when he has the opportunity to killat
prayer:

Now might I do it pat, now he is
praying;
And now I'll do't. And so he goes to heaven;
And so am I revenged.
That would be scann'd:
A villain kills my father; and for that,
I, his sole
son, do this same villain send
To heaven.
O, this is hire and salary, not
revenge.

Hamlet concludes that to be fully revenged, and
thus morally justified, he must kill Claudius in the midst of his sins, as Claudius killed his
father.