Old fellow satisfied, calm, drinking beer in reflection (10)
I believe the answer is:
methuselah
'old fellow' is the definition.
(most long-lived figure in the Bible)
'satisfied calm drinking beer in reflection' is the wordplay.
'satisfied' becomes 'met' (as in 'met the conditions of his contract').
'calm drinking' becomes 'hsuh' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'beer' becomes 'ale' (type of beer).
'in' indicates putting letters inside.
'reflection' says the letters should be written in reverse.
'hsuh' enclosing 'ale' is 'halesuh'.
'halesuh' backwards is 'huselah'.
'met'+'huselah'='METHUSELAH'
Can you help me to learn more?
(Other definitions for methuselah that I've seen before include "so much champagne" , "Old Testament patriarch (very old when he died!)" , "able to hold a lot of drink" , "Large wine bottle - very long-lived man" , "One very old" .)