Criminals dread following grand old monarch and son (9)

I believe the answer is:

gangsters

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

'criminals' is the definition.
(gangster is a kind of criminal)

'grand old monarch and son' is the wordplay.
'grand' becomes 'g' (G is short for grand as in a thousand).
'old' becomes 'angst' (I can't explain this - if you can you should believe this answer much more).
'monarch' becomes 'ER' (abbreviation for Elizabeth Regina, British Queen).
'and' is a charade indicator (letters next to each other).
'son' becomes 's' (genealogical abbreviation for son).
'g'+'angst'+'er'+'s'='GANGSTERS'

'dread following' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for gangsters that I've seen before include "Groups of criminals" , "robbers" .)

I've seen this clue in The Times.

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