What's provided by painter, pretty gloss (9)
I believe the answer is:
Here is my best explanation:
'gloss' is the definition.
'what's provided by painter pretty' is the subsidiary indication.
'what's provided by' indicates the answer is hidden within the clue.
'interpret' is hidden within 'painter pretty'.
(Other definitions for interpret that I've seen before include "explain", "Translate into another language", "Translate or take one's own meaning from", "Make sense of", "Assign one's own meaning to", "Construe", "Gloss needed", "Translate, make sense of", "Explain the meaning of, perhaps a foreign language" and "Discern the meaning of".)