Lawyers and their oddly selected trade (6)
I believe the answer is:
barter
'trade' is the definition.
(synonyms)
'lawyers and their oddly selected' is the wordplay.
'lawyers' becomes 'bar' (I've seen this before).
'and' means one lot of letters go next to another.
'oddly selected' indicates alternate letters.
The alternate letters of 'their' are 'ter'.
'bar'+'ter'='BARTER'
(Other definitions for barter that I've seen before include "Trade, haggle" , "Trade not involving money" , "Give (goods) in exchange" , "Exchange, bargain" , "Trade or swap" .)