something that has bad effects as well as advantages.

Beauty can be a mixed blessing. It gets you a lot of attention but people are less likely to take you seriously.

• do a job on something
• do a land-office business
• do all the running
• do a mischief
• do a moonlight flit
• do a number on
• do a number on someone
• do a number on something
• do any favours
• do anything by halves
• do a power of good
• do a roaring trade
• do a slow burn
• do away with
• do away with someone
• do away with something
• do a world of good
• do battle
• do battle with
• do battle with something
• do best
• do bidding
• do bit
• do by halves
• do credit to