Help President Lincoln with the Ninth Amendment (4)
I believe the answer is:
abet
'help' is the definition.
(I've seen this before)
'president lincoln with the ninth amendment' is the wordplay.
'president lincoln' becomes 'abe' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'the ninth amendment' becomes 't' (9th letter of 'amendment').
'abe'+'t'='ABET'
(Other definitions for abet that I've seen before include "Assist criminally" , "Assist (in doing wrong?)" , "Incite, help" , "Support, aid" , "Assist illegally" .)