Informed team's leader, getting on in years (4)
I believe the answer is:
told
'informed' is the definition.
(telling is a kind of informing)
'team's leader getting on in years' is the wordplay.
'leader' suggests taking the first letters.
'getting on in years' becomes 'old' (getting older).
The initial letter of 'teams' is 't'.
't'+'old'='TOLD'
(Other definitions for told that I've seen before include "Informed; narrated" , "instructed" , "Assured" , "Produced effect; related" , "Authorised - broadcast" .)