Scheme to put fifty in the pot (4)
I believe the answer is:
plan
'scheme' is the definition.
(synonyms)
'fifty in the pot' is the wordplay.
'fifty' becomes 'l' (Roman numeral).
'in' indicates putting letters inside.
'the pot' becomes 'pan' (I've seen this in other clues).
'l' put into 'pan' is 'PLAN'.
'to put' is the link.
(Other definitions for plan that I've seen before include "Formulate" , "Arrangement" , "Aim" , "Stratagem" , "Programme" .)