Agitated by improper fraction, nothing less (7)
I believe the answer is:
frantic
'agitated' is the definition.
('frantic' can be similar in meaning to 'agitated')
'improper fraction nothing less' is the wordplay.
'improper' indicates anagramming the letters.
'nothing' becomes 'o' (looks like zero - 0).
'less' indicates named letters should be taken away.
'fraction' with 'o' taken out is 'fractin'.
'fractin' anagrammed gives 'FRANTIC'.
'by' acts as a link.
(Other definitions for frantic that I've seen before include "Phrenetic" , "Wild - frenzied" , "Wildly agitated" , "Frenetic" , "not collected!" .)