Digits possibly set around zero (4)
I believe the answer is:
toes
'digits' is the definition.
(I know this)
'possibly set around zero' is the wordplay.
'possibly' is an anagram indicator.
'around' is an insertion indicator.
'zero' becomes 'O' (O resembles 0).
'set' anagrammed gives 'tes'.
'tes' going around 'o' is 'TOES'.
(Other definitions for toes that I've seen before include "Foot digits" , "Lower digits" , "What Pobble lacked (Lear)" , "Divisions of foot front" .)