Dots and marks in the backing help pits to merge (7)
I believe the answer is:
stipple
'merge' is the definition.
Although both the answer and definition are verbs in their base form, I cannot see how one could define the other.
'dots and marks in the backing help pits' is the wordplay.
'STIPPLE' is hidden backwards in amongst the letters.
But, I am unsure how the hidden word is indicated.
'to' is the link.
Can you help me to learn more?
(Other definitions for stipple that I've seen before include "Speckle" , "Apply paint in dabs" , "dotty effect" , "Paint, producing a mottled effect" , "Dot" .)