Red Cross is sheltering in place of trade (7)
I believe the answer is:
marxist
'red' is the definition.
(red can mean a communist)
'cross is sheltering in place of trade' is the wordplay.
I cannot quite see how this works, but
'cross' could be 'x' (X is cross-shaped) and 'x' is located in the answer.
'is' is found in the answer.
'place' could be 'mart' (I've seen this before) and 'mart' is located in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for marxist that I've seen before include "Red" , "Revolutionary" , "A leftie once" , "left-winger" , "left-wing" .)