Exchanges damaged red tins around mid-May (6,2)
I believe the answer is:
trades in
'exchanges' is the definition.
(trading in is a kind of exchanging)
'damaged red tins around mid-may' is the wordplay.
'damaged' indicates anagramming the letters.
'around' is an insertion indicator.
'mid' indicates the central letters.
The middle letter of 'may' is 'a'.
'red'+'tins'='redtins'
'redtins' is an anagram of 'trdesin'.
'trdesin' enclosing 'a' is 'TRADES IN'.
(Other definitions for trades in that I've seen before include "exchanges" , "Hands over an object as part payment for a new one" , "'Hands over the old object in part payment for the new (6,2)'" .)