Different aid sent as an alternative (7)
I believe the answer is:
instead
'as an alternative' is the definition.
(synonyms)
'different aid sent' is the wordplay.
'different' indicates anagramming the letters.
'aid'+'sent'='aidsent'
'aidsent' anagrammed gives 'INSTEAD'.
(Other definitions for instead that I've seen before include "Stained (anag)" , "use this as a replacement" , "In place (of)" , "for a change" , "In lieu" .)