Try everything Steve Bell's done, including old works (2,4,5,4)
I believe the answer is:
do ones level best
'try everything' is the definition.
I don't understand the remainder of the clue.
(Other definitions for do ones level best that I've seen before include "Strive" , "Make all possible efforts" , "surpass all others cleaning own storey?" , "Go all out" , "Make every effort" .)