In spades, is a deuce of clubs considered a spade?
The deuce of club and hearts do not considered a spade in the standard game, however there are variants where they do.
From Pagat:

In some versions of Spades, some or all of the four twos are elevated to the top of the spade suit, are ranked in some specified order, and are considered to be spades. The rest of the cards rank as in normal.

For example, in the New York City rules the trump suit ranks is as follows: big joker, small joker, 2♦, 2♠, A, K, Q, J, 10, 9, 8, 7, 6, 5, 4, 3
In the Deuces high rules the trump suit is is as follows:2♠, 2♦, 2♣ 2♡, A, K, Q, J, 10, 9, 8, 7, 6, 5, 4, 3
Those variants are pretty common, and are implemented for example at AI-factory's Spades free app.