Specialist in bastion arranged desistance (10)
I believe the answer is:
abstention
'desistance' is the definition.
Both the definition and answer are singular nouns.
Maybe there's an association between them I don't understand?
'specialist in bastion arranged' is the wordplay.
'specialist' becomes 'ent' (Ear, Nose and Throat specialist).
'in' means one lot of letters goes inside another.
'arranged' indicates an anagram.
'bastion' anagrammed gives 'abstion'.
'ent' placed inside 'abstion' is 'ABSTENTION'.
Can you help me to learn more?
(Other definitions for abstention that I've seen before include "Keeping out of contest" , "forbearance" , "Act of declining to vote" , "endorsing no candidate" , "Withholding of vote" .)