Sketch is baffling, so close play (4,6)
I believe the answer is:
draw stumps
'close play' is the definition.
(cricket)
'sketch is baffling' is the wordplay.
'sketch' becomes 'draw' (I've seen this in other clues).
'is baffling' becomes 'stumps' (stump can mean to confuse or stump).
'draw'+'stumps'='DRAW STUMPS'
'so' is the link.
(Other definitions for draw stumps that I've seen before include "End play" , "Finish (cricket) for the day" , "Stop play" .)