We've been here before, of course:
https://www.theanswerbank.co.uk/Law/Question1631817.html
Nobody here will know exactly what's recorded on police records or, possibly more importantly, exactly
how it's been recorded. (The wording used in police records could affect the way that it's read by anyone who reviews it).
I fully recognise that your question is about security clearance and not about DBS checks but I believe that there are analogies between the two (and that those analogies might not bode at all well for you). So I'll refer you to a couple of things which I think might still be relevant (even if somewhat indirectly):
1. In the investigation which took place after the Soham murders it was found that the police in one part of the country had failed to pass on their concerns about Ian Huntley (who had been accused of sexual offences) to the Cambridgeshire force, so that nothing untoward was flagged up in his DBS check when he applied for a job as a school caretaker. Since then there has been a massive tightening up in the way things are done, so that even the slightest hint of inappropriate behaviour (even though totally unproven) now appears in DBS checks. I suspect that it's highly likely that a similar line is taken with checks for security clearance, meaning that the allegations against you WILL show up and might well count against you.
2. About a decade ago we had a post on AB from a teacher who'd fallen foul of the tightened rules that I've just referred to. He'd been working as a teacher for many years, with no problems at all with CRB checks (as they were then). However when he came to apply for a new job he found that the police had mentioned on his enhanced CRB check that he'd been accused of grooming a child for sex. That was despite the fact that nobody had ever put such an allegation to him. He knew nothing about the matter at all. He didn't know who'd made the accusation, he didn't know which child it referred to and he'd never been questioned by the police, or by anyone else, about the allegation. So he'd had no chance whatsoever to defend himself but his career was totally ruined. (At that time there was no way of challenging information presented on a CRB check. There is now such a mechanism for DBS checks).
So I've got a nasty feeling that you're going to find yourself in a somewhat similar situation with regard to seeking security clearance. i.e. the police will follow a policy of mentioning every allegation made against you in order to 'play safe'. (If they were thinking of charging you with something else, but they didn't think that there was enough evidence to obtain a conviction, they might mention that too. So, like the teacher above, something might show up which you're currently totally unaware of).
Then the person making an assessment based upon that information will also follow a policy of 'playing as safe as possible' (if only to cover their own back if anything were to go wrong), meaning that your application will be refused.
I hope that I'm wrong but I fear that I'll be proved right. Sorry!