First to object if Eric spoils opening (7)
I believe the answer is:
orifice
'opening' is the definition.
(I know that opening can be written as orifice)
'first to object if eric spoils' is the wordplay.
'first to' says to take the initial letters.
'spoils' indicates anagramming the letters.
The initial letter of 'object' is 'o'.
'if'+'eric'='iferic'
'iferic' is an anagram of 'rifice'.
'o'+'rifice'='ORIFICE'
(Other definitions for orifice that I've seen before include "Mouth-like opening" , "8 [OPENING]" , "Hole, opening" , "Bodily opening, mouth of cavity" , "For CIE, I look for an opening" .)