Sought food on behalf of the elderly (7)
I believe the answer is:
foraged
'sought food' is the definition.
(I've seen this before)
'on behalf of the elderly' is the wordplay.
'on behalf of' becomes 'for' (I've seen this before).
'the elderly' becomes 'aged' (I've seen this before).
'for'+'aged'='FORAGED'
(Other definitions for foraged that I've seen before include "Plundered" , "Fear God (anag)" , "Sought out food" , "Looked for food" .)