The most common and most likely answer to this crossword clue is the 7 letter word COMPORT
C
O
M
P
O
R
T
More clues leading to the result COMPORT
Buddy explains!

The straight part
We know that "Act" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case act = comport.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does COMPORT mean?
COMPORT noun- Manner of acting; conduct; deportment.
- To tolerate, bear, put up (with).
- To be in agreement (with); to be of an accord.
- To behave (in a given manner).