Tackled knot tangled round ducks (4,2)
I believe the answer is:
took on
'tackled' is the definition.
(I've seen this in another clue)
'knot tangled round ducks' is the wordplay.
'tangled' is an anagram indicator.
'round' is an insertion indicator.
'ducks' becomes 'OO' (two O's - duck means zero in cricket).
'knot' anagrammed gives 'tkon'.
'tkon' going around 'oo' is 'TOOK ON'.
(Other definitions for took on that I've seen before include "Employed" , "Got upset < , did recruit" , "challenged" .)