Paint with new colour for one such as five? (5,6)
I believe the answer is:
prime number
'as five?' is the definition.
The definition and answer can be both quantities as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'paint with new colour for one' is the wordplay.
I cannot really see how this works, but
'paint' could be 'prime' (priming is a kind of painting) and 'prime' is found in the answer.
'new' could be 'n' (abbreviation as in New Testament NT) and 'n' is present in the answer.
'colour' could be 'umber' (umber is a kind of colour) and 'umber' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'such' acts as a link.
Can you help me to learn more?
(Other definitions for prime number that I've seen before include "Maybe two or three" , "2 or 3 -- but not 4" , "Two or three perhaps" , "one alone can always divide" , "One with no divisors" .)