Curse, as sheep and lamb go astray (9)
I believe the answer is:
blaspheme
'curse' is the definition.
(synonyms)
'sheep and lamb go astray' is the wordplay.
'and' says to put letters next to each other.
'go astray' is an anagram indicator.
'sheep'+'lamb'='sheeplamb'
'sheeplamb' with letters rearranged gives 'BLASPHEME'.
'as' acts as a link.
(Other definitions for blaspheme that I've seen before include "Speak profanely" , "Talk irreverently about God and sacred things" , "Say irreverent things about God" , "Speak irreverently about God" , "Utter obscenities or profanities" .)