For an alien to be after money, is permitted (3)
I believe the answer is:
let
'is permitted' is the definition.
(to let something happen is to permit it)
'for an alien to be after money' is the wordplay.
I cannot quite see how this works, but
'alien' could be 'et' (extra terrestrial) and 'et' is located in the answer.
'money' could be 'l' (L can mean 'pounds') and 'l' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for let that I've seen before include "Allow or rent" , "Award (a contract)" , "Umpire's decision" , "Reason for scrubbing service" , "Disappoint or fail to support - ... down" .)