Stuck up in two ways? (5)
I believe the answer is:
proud
'stuck up' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for proud that I've seen before include "Self-satisfied - stately - protruding" , "Haughty - sticking out" , "Feeling self-respect - projecting from a surface" , "Guilty of deadly sin" , "Walking tall" .)