Set one plus one between 50 and 500 (4)
I believe the answer is:
laid
'set' is the definition.
(synonyms)
'one plus one between 50 and 500' is the wordplay.
'one plus one' becomes 'ai' (I am not sure about this - if you are sure you should believe this answer much more).
'between' means one lot of letters goes inside another.
'50' becomes 'l' (Roman numeral).
'and' says to put letters next to each other.
'500' becomes 'D' (Roman numeral for 500).
'l'+'d'='ld'
'ai' placed inside 'ld' is 'LAID'.
Can you help me to learn more?
(Other definitions for laid that I've seen before include "Produced eggs" , "Wagered" , "Deposited" , "Put down like dial" , "Doze" .)