Informed the aged at a treatment centre (4)
I believe the answer is:
told
'informed' is the definition.
(telling is a kind of informing)
'the aged at a treatment centre' is the wordplay.
'the aged' becomes 'old' (I've seen this before).
'at' says to put letters next to each other (I've seen this in other clues).
'centre' means to look at the middle letters.
The centre of 'treatment' is 't'.
'old' after 't' is 'TOLD'.
(Other definitions for told that I've seen before include "Authorised - broadcast" , "Related (a story)" , "Informed; narrated" , "Produced effect; related" , "instructed" .)