Making progress in appointing a principal (7,5)

I believe the answer is:

getting ahead

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'making progress' is the definition.
The answer and definition can be both related to change as well as being present participle verbs.
Maybe they are linked in a way I don't understand?

'appointing a principal' is the wordplay.
'appointing' becomes 'getting' (I can't justify this - if you can you should give a lot more credence to this answer).
'principal' becomes 'head' (synonyms).
'getting'+'a'+'head'='GETTING AHEAD'

'in' acts as a link.

Can you help me to learn more?

I've seen this clue in The Irish Independent.

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