Element of Muriel’s Wedding perhaps too mushy (10)
I believe the answer is:
apostrophe
'element of muriel's wedding' is the definition.
I can't judge whether this defines the answer.
'perhaps too mushy' is the wordplay.
'mushy' indicates an anagram (letters mushed up).
'perhaps'+'too'='perhapstoo'
'perhapstoo' with letters rearranged gives 'APOSTROPHE'.
Can you help me to learn more?
(Other definitions for apostrophe that I've seen before include "in Charley's Aunt ?" , "Sign of omission" , "Letter omission indicator" , "Where character may be absent" , "Part of man's" .)