Leader of Cubs, about to enter game, disheartened Scouts (7)
I believe the answer is:
tigress
'leader of cubs' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'about to enter game disheartened scouts' is the wordplay.
'about' becomes 're' (regarding).
'to' says to put letters next to each other (I've seen this in other clues).
'enter game' becomes 'tig' (I can't explain this - if you can you should give a lot more credence to this answer).
'disheartened' says to hollow out the word (remove centre letters) (the middle or heart is removed).
'scouts' with its middle taken out is 'ss'.
're' put after 'tig' is 'tigre'.
'tigre'+'ss'='TIGRESS'
Can you help me to learn more?
(Other definitions for tigress that I've seen before include "Wild cat (female)" , "Amazon, say" , "Large female cat" , "Passionate woman" , "Female striped cat" .)