Group of fifty captured by famous general (7)
I believe the answer is:
cluster
'group of' is the definition.
'cluster' can be an answer for 'group' (I've seen this before). I'm not certain of the 'of' bit.
'fifty captured by famous general' is the wordplay.
I cannot really understand how this works, but
'fifty' could be 'l' (Roman numeral) and 'l' is found in the answer.
'general' could be 'custer' (I've seen this before) and 'custer' is present in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for cluster that I've seen before include "Small group" , "Come together" , "Close group of things" , "Closely-spaced group" , "Thick grouping of similar things" .)