Without beer regularly, teams end resentful (10)
I believe the answer is:
embittered
'resentful' is the definition.
(I've seen this before)
'without beer regularly teams end' is the wordplay.
'without' is an insertion indicator.
'beer' becomes 'bitter' (bitter is a type of beer).
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'teams'+'end'='teamsend'
The alternate letters of 'teamsend' are 'emed'.
'bitter' going inside 'emed' is 'EMBITTERED'.
(Other definitions for embittered that I've seen before include "Made more sour" , "Made resentful" .)