Old writer extremely lazy in public (6)
I believe the answer is:
openly
'in public' is the definition.
(I've seen this in another clue)
'old writer extremely lazy' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'writer' becomes 'pen' (something which writes).
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'lazy' with its centre removed is 'ly'.
'o'+'pen'+'ly'='OPENLY'
(Other definitions for openly that I've seen before include "In full view" , "In an overt way" , "Frankly, honestly" , "In frank and candid manner" , "Overtly" .)