Against joining eccentric marquis in a study of old artefacts (14)
I believe the answer is:
antiquarianism
'study of old artefacts' is the definition.
'antiquarianism' can be an answer for 'study' (I have seen 'Study of past' mean 'antiquarianism' so perhaps 'study' could also mean 'antiquarianism'). I am not certain of the 'of old artefacts' bit.
'against joining eccentric marquis in a' is the wordplay.
'against' becomes 'anti' (I've seen this before**).
'joining' says to put letters next to each other.
'eccentric' indicates an anagram.
'marquis'+'in'+'a'='marquisina'
'marquisina' is an anagram of 'quarianism'.
'anti'+'quarianism'='ANTIQUARIANISM'
Can you help me to learn more?
(Other definitions for antiquarianism that I've seen before include "Study of past" , "A love of rare books and old things" , "The study or collection of old things" .)