Despite the CLub support South must show their Spade suit because North has not denied holding four Spades.

North's 2♥  shows 16 points and is a reverse because it forces South to the 3-level if they wish to show preference for North's first bid suit.

At teams South probably bids 5♣ but this is Pairs. If North has a Diamond Stop then 3NT should be on and is likely to score higher than 5♣ .

This is where a Convention called Fourth Suit Forcing comes into it's own. When your side have bid three suits then bidding the fourth suit asks partner to describe their hand further. In particular it says bid NT if you have a stop in the fourth suit. It is forcing for one round or forcing to game when used at the 3-level.

So 3♦ here asks North to describe their hand further and with the ♦ A North bids 3NT and earns N/S a near top.