There's a case for folding this hand pre, both the initial raise and then to the 3-bet which, from SB, is likely a tight range, and may have better Axxx that crushes us. It's double-suited to the A and K, but the 7 and 3 are terrible. I recall a poker video which suggested to imagine double suited hands are single suited, because double suited hands can look deceptively pretty; if this was AK73 single suited to the A it'd go straight in the muck from MP. I would probably open it from the CO, however (for full pot).
