For her, it's all wrong to beat the back of the queue (4)
I believe the answer is:
ella
'for her' is the definition.
'it's all wrong to beat the back of the queue' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'all' is 'lla' which is within the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ella that I've seen before include "Diminutive of Eleanor" , "- Wheeler Wilcox, US poet" , "Ms Fitzgerald" , "- - Fitzgerald (mus.)" , ".... Fitzgerald, late great jazz diva" .)