Large number of men diet, taking heart in fasting (8)
I believe the answer is:
regiment
'large number of men diet taking heart in fasting' is the definition.
I can't tell whether this defines the answer.
'diet taking heart in fasting' is the wordplay.
'diet' becomes 'regimen' (a diet is a certain eating regimen).
'taking' is a charade indicator (letters next to each other).
'heart in' indicates the central letters.
The middle letter of 'fasting' is 't'.
'regimen'+'t'='REGIMENT'
Can you help me to learn more?
(Other definitions for regiment that I've seen before include "a whole lot of them" , "Military group" , "Military unit" , "Metering (anag) - army unit" , "Section of an army" .)