In proportion, Elton confused about acceptance (10)
I believe the answer is:
toleration
'acceptance' is the definition.
(synonyms)
'in proportion elton confused about' is the wordplay.
'in proportion' becomes 'ratio' (I've seen this before).
'confused' is an anagram indicator.
'about' means one lot of letters goes inside another.
'elton' with letters rearranged gives 'tolen'.
'ratio' put inside 'tolen' is 'TOLERATION'.
(Other definitions for toleration that I've seen before include "liberality" , "Forbearance" , "Patience" , "Allowance of what is not approved" , "Indulgence" .)