Shed tears about principal character of lager lout (4)
I believe the answer is:
slob
'lout' is the definition.
(thesaurus)
'shed tears about principal character of lager' is the wordplay.
'shed tears' becomes 'sob'.
'about' means one lot of letters goes inside another.
'principal character of' suggests taking the first letters.
The initial letter of 'lager' is 'l'.
'sob' going around 'l' is 'SLOB'.
(Other definitions for slob that I've seen before include "Fat, idle person" , "Slovenly layabout" , "Uncouth person" , "'Slovenly, messy person (4)'" , "Slovenly, dirty type" .)