Elbow’s good in, eg, Goya’s Naked Maja (5)
I believe the answer is:
nudge
'elbow's' is the definition.
('nudge' can be a synonym of 'elbow')
'good in eg goya's naked maja' is the wordplay.
'good' becomes 'g' (abbreviation).
'in' means one lot of letters goes inside another.
'eg goya's naked maja' becomes 'nude' (Goya's Naked Maja is a nude painting).
'g' placed inside 'nude' is 'NUDGE'.
(Other definitions for nudge that I've seen before include "Push with the elbow" , "Push (with a wink?)" , "Gentle encouragement" , "Prod gently with elbow" , "Encouraging prompt" .)