Same level within carpark (3)
I believe the answer is:
par
'same level' is the definition.
(par is an average or standard level)
'within carpark' is the wordplay.
'within' indicates a hidden word.
'PAR' is hidden within 'carpark'.
(Other definitions for par that I've seen before include "normal amount" , "Average or normal score" , "Average score for round of golf" , "Normal level or standard" , "A number of golfing" .)