When the moderator leaves the room, arrange to seal the deal. (5)
I believe the answer is:
trade
'the deal' is the definition.
(synonyms)
'when the moderator leaves the room arrange to seal' is the wordplay.
I cannot really see how this works, but
'when' could be 'e' (I've seen this in other clues) and 'e' is found in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'rad' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for trade that I've seen before include "Calling" , "Commercial exchange of goods and services" , "Business - (kind of) wind" , "Barter, do business" , "Commerce - traffic" .)