Writing fluid on page provides colour (4)
I believe the answer is:
pink
'colour' is the definition.
(pink is a kind of colour)
'writing fluid on page' is the wordplay.
'writing fluid' becomes 'ink' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'page' becomes 'p'.
'ink' after 'p' is 'PINK'.
'provides' is the link.
(Other definitions for pink that I've seen before include "Ros colour" , "(Shade of) flower" , "Pale red" , "Knock (of engine) - garden flower" , "Rather embarrassed" .)