One responsible for publication of Serious Disruption Order is dropped (6)

I believe the answer is:

issuer

I'm a little stuck... Click here to teach me more about this clue!

'one responsible for publication of serious disruption order' is the definition.
I can't tell whether this defines the answer.

'is dropped' is the wordplay.
'dropped' becomes 'suer' (I can't justify this - if you can you should give a lot more credence to this answer).
'is'+'suer'='ISSUER'

Can you help me to learn more?

(Other definitions for issuer that I've seen before include "publishing house?" , "one responsible for 12D [PUBLICATION] ?" , "One distributing for use" , "publisher" .)

I've seen this clue in The Guardian.

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