Thanks poet for knight's garment (6)
I believe the answer is:
tabard
'knight's garment' is the definition.
(I've seen this in another clue)
'thanks poet' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'poet' becomes 'bard' (bard is a kind of poet).
'ta'+'bard'='TABARD'
'for' is the link.
(Other definitions for tabard that I've seen before include "Inn where pilgrims met" , "Herald's jacket" , "Historical tunic" , "Jacket worn by a herald" , "Clobber" .)