There's more than one girl Les is upset about (7)
I believe the answer is:
several
'there's more than one' is the definition.
I can't tell whether this defines the answer.
'girl les is upset about' is the wordplay.
'girl' becomes 'vera' ().
'is upset' says the letters should be written in reverse (I've seen 'being upset' mean this).
'about' indicates putting letters inside.
'les' backwards is 'sel'.
'vera' going into 'sel' is 'SEVERAL'.
Can you help me to learn more?
(Other definitions for several that I've seen before include "Sundry, distinct" , "Indefinite number more than two or three, but not many" , "Assorted" , "Some participants" , "quite a lot" .)