Tip for old schoolmarm out of make-up? (11)

'out of make-up?' is the definition.
Although both the answer and definition are adjectives, I can't understand how they can define each other.

'tip for old schoolmarm' is the wordplay.
I cannot really understand how this works, but
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is found within the answer.
an anagram of 'schoolmarm' is 'chrmosomal' which is within the left over letters.
No letters remain.
This explanation may well be incorrect...

Can you help me to learn more?