It's most important - don't take in short dress and top (8)
I believe the answer is:
dominant
'it's most important' is the definition.
I can't tell whether this defines the answer.
'don't take in short dress and top' is the wordplay.
'take in' means one lot of letters goes inside another.
'short' means to remove the last letter.
'dress' becomes 'mini' (I have seen 'Short dress' mean 'mini' so perhaps 'dress' could also mean 'mini').
'top' says to take the initial letters.
The first letter of 'and' is 'a'.
'mini' with its last letter taken away is 'min'.
'min'+'a'='mina'
'dont' enclosing 'mina' is 'DOMINANT'.
Can you help me to learn more?
(Other definitions for dominant that I've seen before include "alpha male?" , "a key" , "Having a commanding influence or towering over" , "In a controlling position" , "Ascendant" .)