Press in or out (4)
I believe the answer is:
iron
'press' is the definition.
(ironing is a kind of pressing)
'in or out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'in'+'or'='inor'
'inor' anagrammed gives 'IRON'.
(Other definitions for iron that I've seen before include "stern" , "Metallic chemical element" , "Club; element" , "Smooth; element" , "uncompromising" .)