Makes one's mark as a newcomer (5,2)
I believe the answer is:
signs on
'makes one's' is the definition.
The answer and definition can be both to do with social activities as well as being verbs in their -s form.
Perhaps they are linked in a way I don't understand?
'mark as a newcomer' is the wordplay.
I cannot really see how this works, but
'mark' could be 'sign' (synonyms) and 'sign' is located in the answer.
'as' could be 'so' (I've seen this in other clues) and 'so' is located in the answer.
A single letter 'n' remains which might be clued in a way I don't see.
This may be the basis of 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" .)