Colour match with an outline of felt tip, perhaps (3,5)
I believe the answer is:
pea green
'colour' is the definition.
(pea green is a kind of colour)
'match with an outline of felt tip perhaps' is the wordplay.
I cannot quite see how this works, but
'match' could be 'agree' (as in two tallies agreeing or matching) and 'agree' is found within the answer.
The remaining letters 'pen' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for pea green that I've seen before include "Vegetable shade?" , "beautiful colour for a boat" , "Bright vegetable colour" , "colour of Lear's boat" , "Bright colour with a yellow tinge - eager pen (anag)" .)