It may need stroking (3)
I believe the answer is:
'it may need stroking' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ego that I've seen before include "Self-esteem, conceit" , "Selfishness" , "See 21 Down" , "Conscious mind" , "(Self-assertive) personality" .)