Each clue below can be answered by a two-word phrase. These phrases will have something in common.

1. Baseball feat
2. Asthmatic's concern
3. Brave front
4. Period of radioactivity

HINT:
The first words of the answers are:
1. Double
2. Air
3. Game
4. Half

Answers:

1. Double play
2. Air quality
3. Game face
4. Half life

What the phrases have in common:

Both words in each phrase can be followed by TIME:

1. Double time - Play time
2. Air time - Quality time
3. Game time - Face time
4. Half time - Life time

Credit: NY Times Crossword
Scott Atkinson - Oct. 8, 2009