Tank Age is not so much a factor as stability is. A tank can be a year old and if the water parameters are not all in place, your tank is not suitable for a clam.
Assuming your temperature, salinity, pH, calcium, etc. are all where they should be, you should also have residual nitrates and phosphates in your tank left for clams as discussed in previous threads.
If SPS can be kept in your tank, so can clams with regard to lighting. Nothing is too much if the clams are properly acclimated.