Fish out many a man to order (7)
I believe the answer is:
command
'to order' is the definition.
(I know that command is a more specific form of the action enjoin)
'fish out many a man' is the wordplay.
'fish' becomes 'cod' (type of fish).
'out' means to remove the last letter.
'many' becomes 'M' (Roman numeral for a thousand).
'a man' becomes 'mand' (I can't explain this - if you can you should give a lot more credence to this answer).
'cod' with its final letter removed is 'co'.
'co'+'m'+'mand'='COMMAND'
Can you help me to learn more?
(Other definitions for command that I've seen before include "Bidding" , "Instruction, order" , "Authoritative order" , "Fiat" , "Order; dominate" .)