Leader terribly glum about love (5)
I believe the answer is:
mogul
'leader' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'terribly glum about love' is the wordplay.
'terribly' indicates an anagram.
'about' indicates putting letters inside.
'love' becomes 'o' (love means zero in tennis).
'glum' with letters rearranged gives 'mgul'.
'mgul' going around 'o' is 'MOGUL'.
Can you help me to learn more?
(Other definitions for mogul that I've seen before include "Mound of hard snow on ski-slope" , "Indian emperor - important person" , "Magnate (from India?)" , "Bashaw" , "Very wealthy or powerful business person" .)