Enclave at the height of their power? For sure.
The securitron army (and local gangs) would put up a good fight but between the Enclave's vertibird fleet, special forces squads, and destabilization efforts that would've come in before a real battle House would've been blown away.
Holding it would be the greater issue. As first they'd need to put their boot down on the locals to keep them in line, then they'd have to keep it out of everyone else's hands.