Looked on behalf of the elderly (7)
I believe the answer is:
foraged
'looked' is the definition.
Although both the answer and definition are past participle verbs, I can't see how one could define the other.
'on behalf of the elderly' is the wordplay.
'on behalf of' becomes 'for' (eg speaking on behalf of or for someone else).
'the elderly' becomes 'aged' (I've seen this before).
'for'+'aged'='FORAGED'
Can you help me to learn more?
(Other definitions for foraged that I've seen before include "Sought out food" , "Plundered" , "Fear God (anag)" , "Looked for food" .)