It's a departure from the norm for Lincoln getting Republican quota (10)
I believe the answer is:
aberration
'it's a departure' is the definition.
(aberration is a kind of departure)
'lincoln getting republican quota' is the wordplay.
'lincoln' becomes 'abe' (I've seen this in another clue).
'getting' is a charade indicator (letters next to each other).
'republican' becomes 'r' (abbreviation).
'quota' becomes 'ration' (I've seen this before).
'abe'+'r'+'ration'='ABERRATION'
'from the norm for' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for aberration that I've seen before include "Slip" , "mistake" , "instability" , "irregularity" , "Deviation from the accepted norm" .)