A French worker hides bitterness — it's not chivalrous (9)
I believe the answer is:
ungallant
'not chivalrous' is the definition.
(I've seen this before)
'a french worker hides bitterness' is the wordplay.
'a french' becomes 'un' ('a' in French).
'worker' becomes 'ant' (worker is a type of ant).
'hides' means one lot of letters goes inside another.
'bitterness' becomes 'gall' (synonyms).
'un'+'ant'='unant'
'unant' placed around 'gall' is 'UNGALLANT'.
'it's' is the link.
(Other definitions for ungallant that I've seen before include "ignoble" , "lacking courtesy" , "Not chivalrous" , "Discourteous" .)