Sitting down to eat around one — not actually initially realistic (10)
I believe the answer is:
attainable
'realistic' is the definition.
(realistic can mean possible or attainable)
'sitting down to eat around one not actually initially' is the wordplay.
'sitting down to eat' becomes 'at table' (sitting at the dinner table).
'around' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'initially' says to take the initial letters.
The initial letters of 'not actually' is 'na'.
'i'+'na'='ina'
'attable' enclosing 'ina' is 'ATTAINABLE'.
(Other definitions for attainable that I've seen before include "Reachable" , "that may be arrived at" , "Within reach" .)