Sketchy subject? (3)
I believe the answer is:
art
'sketchy subject?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for art that I've seen before include "''... is long and life is short''" , "Skill in a specified thing" , "For example, Blakey's creative" , "eg Painting" , "crafty conduct" .)