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