Possible Clues:

• Unclear situation
• It's open to interpretation (Var.)
• Easily handled in vast, endless, vague domain
• It's hard to describe precisely where work is inadequate
• One of undefined boundaries
• Matter about which there is no certainty
• Pensioners' field that's not properly marked out
• Agree to differ about rejecting fish, where there's doubt
• One of unclear boundaries
• Upset work unit should take a year off? It's unclear