Mother in AA not losing love for the hard stuff (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

DAM (mother) in AA and N o T losing ‘o’ (love). We had to check the definition – adamant is a name applied by the ancients to various hard substances. It is also an obsolete term for diamond, the hardest substance although there is no indication in the clue that we are looking for an ‘old’ meaning.