Gerald Ford's introduction aroused warning signal (3,4)
I believe the answer is:
red flag
'warning signal' is the definition.
(I've seen this before)
'gerald ford's introduction aroused' is the wordplay.
'introduction' says to take the initial letters.
'aroused' is an anagram indicator (letters roused or stirred up into a new form).
The first letter of 'fords' is 'f'.
'gerald'+'f'='geraldf'
'geraldf' with letters rearranged gives 'RED FLAG'.
(Other definitions for red flag that I've seen before include "A flyer" , "Warning sign" , "Socialist anthem" , "Emblem of socialist revolution or danger" , "left-wing message?" .)