Poor Herbert and Ada are worn out (10)
I believe the answer is:
threadbare
'worn out' is the definition.
(I've seen this before)
'poor herbert and ada' is the wordplay.
'poor' indicates anagramming the letters.
'and' says to put letters next to each other (I've seen this in other clues).
'herbert' after 'ada' is 'adaherbert'.
'adaherbert' anagrammed gives 'THREADBARE'.
'are' acts as a link.
(Other definitions for threadbare that I've seen before include "Frayed" , "Has little nap" , "cliche-ridden" , "Tired" , "deprived of nap" .)