Sam left struggling for aid (4)
I believe the answer is:
alms
'aid' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'sam left struggling' is the wordplay.
'left' becomes 'l' (common abbreviation).
'struggling' indicates anagramming the letters.
'sam'+'l'='saml'
'saml' with letters rearranged gives 'ALMS'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for alms that I've seen before include "Charitable donations to poor" , "handed over as charity" , "Charitable relief" , "Charity for poor" , "Charitable aid to poor" .)