Some outdated ideas passed muster (3)
I believe the answer is:
did
'passed muster' is the definition.
'did' can be an answer for 'passed' (doing is a kind of passing). I am unsure of the 'muster' bit.
'some outdated ideas' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'DID' is hidden within 'outdated ideas'.
Can you help me to learn more?
(Other definitions for did that I've seen before include "Performed an action" , "Accomplished" , "Carried out, performed" , "was satisfactory" , "Acted" .)