Relieve bit of exhaustion after brewing vital ale (9)
'relieve' is the definition.
(I've seen this before)
'bit of exhaustion after brewing vital ale' is the wordplay.
'bit of' indicates taking the first letters.
'after' says to put letters next to each other.
'brewing' indicates an anagram.
The initial letter of 'exhaustion' is 'e'.
'vitalale' is an anagram of 'alleviat'.
'e' after 'alleviat' is 'ALLEVIATE'.
(Other definitions for alleviate that I've seen before include "Make better", "Make less severe, say suffering", "dull", "Assuage", "Soothe".)