Sheep and lamb going astray? Curse (9)
I believe the answer is:
blaspheme
'curse' is the definition.
(I know that curse can be written as blaspheme)
'sheep and lamb going astray?' is the wordplay.
'and' means one lot of letters go next to another.
'going astray?' is an anagram indicator.
'sheep' put after 'lamb' is 'lambsheep'.
'lambsheep' is an anagram of 'BLASPHEME'.
(Other definitions for blaspheme that I've seen before include "Utter obscenities or profanities" , "Speak irreverently about God" , "Swear" , "Talk irreverently about God and sacred things" , "Curse, profane" .)