warspite1 is completely correct. HQs (in the case in question HQ Georges) can provide defensive HQ support to themselves, even if they're the only defending units.
It's right there in the proverbial black and white:
the inactive side announces HQ support for target hexes. [Emphasis mine
It must be in, or adjacent to, the target hex.
The hex is the target - that is to say, the HQ supports
all participating units in the hex. So if the HQ is the only unit in the hex and it supports itself, so be it.
Further, the rules would be contradicting themselves if we took the final clause of:
It can’t provide support to a unit it does not co-operate with, to an adjacent hex if it is separated from it by an impassable hexside, or if its own hex is also being attacked.
to mean that HQ's can't support their own hex, when
the immediately preceding sentence allows the HQ to be in the target hex (that is, the hex being attacked).
The parsing of what an HQ can't support is modified by the word "to", and thus is as follows:
- An HQ can't support a hex if it contains a unit it does not cooperate with (it follows, necessarily, that this is an adjacent hex since the HQ couldn't stack with the non-cooperating unit)
- An HQ can't support an adjacent hex if the intervening hexside is impassible or if the hex the HQ is in is also being attacked.
(Also, I'm not sure why quoting dictionary definitions of common uses is applicable for a 'jargonised' terminology such as the rules of (M)WiF, and at any rate common usage of 'support' absolutely does include self-support.)