Bothered about article (3)
I believe the answer is:
the
'article' is the definition.
(the 'definite article' part of speech)
'bothered about' is the wordplay.
'about' indicates the answer is hidden within the clue.
'THE' can be found hidden inside 'bothered'.
(Other definitions for the that I've seen before include "15, 16 One given taste of own medicine" , "Finis" , "and 24 Down: Similar things" , "Born - - - - - - - - (carol)" , "That particular one" .)