Price is both officer and saint (4)
I believe the answer is:
cost
'price' is the definition.
(synonyms)
'both officer and saint' is the wordplay.
'both officer' becomes 'co' (Commanding Officer abbreviation. I am not sure about the 'both' bit.).
'and' means one lot of letters go next to another.
'saint' becomes 'st' (abbreviation).
'co'+'st'='COST'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for cost that I've seen before include "Be priced at" , "Outlay required to buy" , "Come to" , "Total spent for goods or services" , "Amount to pay" .)