Gym girl from south and I remain mostly gloomy about future (11)
I believe the answer is:
pessimistic
'gloomy about future' is the definition.
(pessimistic about future prospects)
'gym girl from south and i remain mostly' is the wordplay.
I cannot quite understand how this works, but
'gym' could be 'pe' (short for Physical Education) and 'pe' is found within the answer.
'girl' could be 'misti' and 'misti' is located in the answer.
'south' could be 's' (synonyms) and 's' is located in the answer.
'i' is found in the answer.
This explanation may well be incorrect...
(Other definitions for pessimistic that I've seen before include "Lacking hope for the future" , "Not seeing the bright side" , "Looking on the black side" , "Tending to look on the dark side of things" , "Hopeless!" .)