Conceit, for example, shown by Oscar (3)
I believe the answer is:
ego
'conceit' is the definition.
(I've seen this before)
'example shown by oscar' is the wordplay.
'example' becomes 'eg'.
'shown by' means one lot of letters go next to another.
'oscar' becomes 'o' (phonetic alphabet: alpha, bravo, charlie etc.).
'eg'+'o'='EGO'
'for' is the link.
(Other definitions for ego that I've seen before include "Selfishness" , "number one" , "Self-esteem or self-importance" , "Vowel to disappear, < say another" , "One's sense of self-importance" .)