Zero in, turning attention away from earl (3)
I believe the answer is:
nil
'zero' is the definition.
('nil' can be a synonym of 'zero')
'in turning attention away from earl' is the wordplay.
'turning' is a reversal indicator.
'attention' becomes 'ear' (ear is a kind of attention).
'away from' is a deletion indicator.
'in' in reverse letter order is 'ni'.
'earl' with 'ear' taken away is 'l'.
'ni'+'l'='NIL'
(Other definitions for nil that I've seen before include "Nothing found in senility" , "Nix, nada, nothing" , "You get nothing" , "Score of nought" , "Don't despair - . . . desperandum" .)