Makes one's mark as a newcomer (5,2)
I believe the answer is:
signs on
'makes one's' is the definition.
The definition and answer can be both to do with social activities as well as being verbs in their -s form.
Maybe they are linked in a way I don't understand?
'mark as a newcomer' is the wordplay.
I cannot quite see how this works, but
'mark' could be 'sign' (synonyms) and 'sign' is found within the answer.
'as' could be 'so' (I've seen this in other clues) and 'so' is found within the answer.
A single letter 'n' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for signs on that I've seen before include "Hires" , "Employs" .)