"Appropriate for a sales agent," take back (6)
I believe the answer is:
proper
'appropriate' is the definition.
(similar in meaning)
'for a sales agent take back' is the wordplay.
'for' becomes 'pro' (as in being 'pro' or in favour of something).
'a sales agent' becomes 'rep' (I've seen this in another clue).
'take back' is a reversal indicator (I've seen 'taken back' mean this).
'rep' backwards is 'per'.
'pro'+'per'='PROPER'
(Other definitions for proper that I've seen before include "Correct; formal" , "Conventional" , "Real; genuine" , "Correct, decent" , "Right or suitable" .)