First thing you have to determine is whether that hand is worth a game force. That depends on the location of your honor cards, your support for opener's hearts, spot cards like 10's and 9's, etc. Also, whether your partner tends to open light. Do you have 3 card heart support and are you playing 5 card majors? Then, what bidding system are you playing. I don't (and won't) play Acol, but I'm guessing that 2♣ would be a common response. In a "standard" 2/1 game force system, if you decide this hand is worth a game force, then 2♣ would usually be the response (i.e. if club were ♣xxxxx you may decide to treat clubs as a 4 card suit and respond 1♠. If you decide that hand is only an invitational bid, then 1♠ would be the choice. I'm not going to say anything bad about MAFIA responses, but just note that if responder bids 2 suits, the suit lengths are ambiguous and you need well defined agreements on subsequent rounds to figure out what's going on.