Cut steer out for a period (9)
I believe the answer is:
trimester
'period' is the definition.
(I know that trimester is a type of period)
'cut steer out' is the wordplay.
'cut' becomes 'trim' (trimming is a kind of cutting).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'steer' is an anagram of 'ester'.
'trim'+'ester'='TRIMESTER'
'for a' acts as a link.
(Other definitions for trimester that I've seen before include "Period of three months" , "US academic term" , "American term" , "academic session" , "part of college year" .)