Slowly finishes sketches by Hopper - for the most part within reach (5,2,1,5)
I believe the answer is:
draws to a close
'slowly finishes' is the definition.
'sketches by hopper for the most part within reach' is the wordplay.
'sketches' becomes 'draws' (I've seen this before).
'by' says to put letters next to each other.
'hopper' becomes 'toad' (something that hops).
'for the most part' means to remove the last letter.
'within reach' becomes 'close'.
'toad' with its final letter taken away is 'toa'.
'draws'+'toa'+'close'='DRAWS TO A CLOSE'
(Another definition for draws to a close that I've seen is " Ends".)