"By all means, go ahead!"

PLEASEDO

Think of a polite way to encourage someone to proceed that blends two common words together.

The phrase "By all means, go ahead!" is a polite way of giving permission, and "please do" fits that meaning perfectly. In crosswords, answers are often written as one word without spaces, so "PLEASEDO" combines the two words into a single solution. The clue plays on the literal interpretation of the phrase while hinting at the merged spelling.