Finding a 5-Pointed Star in polynomial time
If $G=(V,E)$ is a graph, how many subsets of $V$ of size $5$ exist?

If there is a 5-clique, one of this subsets is a clique.

Spoilers below:


   There are ${|V| \choose 5}$ possible subsets to check, that is, at most $|V|^5$ options, which is polynomial in the input. This is NOT the case for an arbitrary $k$, since $|V|^k$ might be exponential in the input, and this is why $\text{CLIQUE} \notin P$ (unless P=NP, agghh.).