Care! Organ replacement can lead to overbearing pomposity (9)
I believe the answer is:
arrogance
'overbearing pomposity' is the definition.
'arrogance' can be an answer for 'pomposity' (I've seen this in another clue). I'm not certain of the 'overbearing' bit.
'care organ replacement' is the wordplay.
'replacement' indicates an anagram.
'care'+'organ'='careorgan'
'careorgan' is an anagram of 'ARROGANCE'.
'can lead to' acts as a link.
Can you help me to learn more?
(Other definitions for arrogance that I've seen before include "Overbearing attitude of pride and insolence" , "Aggressive assertiveness" , "Overbearing conceit" , "Overbearing haughtiness" , "Overweening self-importance" .)