Budget speech, not one's first (6)
I believe the answer is:
'budget' is the definition.
(I've seen this in other clues)
'speech not one's first' is the wordplay.
'speech' becomes 'oration' (oration is a kind of speech).
'not' indicates named letters should be taken away.
'one's first' becomes 'o' (1st letter of 'one').
'oration' with 'o' taken out is 'RATION'.
(Other definitions for ration that I've seen before include "Limit supply of (eg, food)" , "Portion, share" , "One's allotted portion" , "Limit issue" , "Quota" .)