Make dark to please greatly (7)
I believe the answer is:
delight
'please greatly' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for delight that I've seen before include "charm" , "''A lonely impulse of ...'' (Yeats)" , "Greensleeves was mine" , "Greatly please" , "See 5" .)