Selfish oddball with attempt to oust Conservative (10)
I believe the answer is:
egocentric
'selfish' is the definition.
(I've seen this before)
'oddball with attempt to oust conservative' is the wordplay.
I cannot quite see how this works, but
'attempt' could be 'go' (go is a kind of attempt) and 'go' is found in the answer.
'conservative' could be 'c' (UK political abbreviation) and 'c' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for egocentric that I've seen before include "Self-obsessed" , "Self-seeking" , "Not thinking of others" , "Self-interested" , "Self-absorbed" .)