Clue: 'Go to work on …', not good? At least it wasn't blasphemous (4)
Answer: EGAD
Explanation: Definition: At least it wasn't blasphemous
"EGG AD" (of which "Go to work on.. " was the start of the slogan) less (one) G. Fay Weldon was involved in creating the campaign, though she denies coming up with the actual words – "egad!" is a minced oath, an evasion of "oh God" or similar