Jack Grealish's girl, maybe, supping wine in France, being patriotic (4-6)
I believe the answer is:
flag-waving
'patriotic' is the definition.
(similar in meaning)
'jack grealish's girl maybe supping wine in france being' is the wordplay.
I cannot really understand how this works, but
'jack' could be 'flag' (I've seen this before) and 'flag' is present in the answer.
'girl' could be 'vin' and 'vin' is located in the answer.
'being' could be 'wag' (wag is a kind of being) and 'wag' is present in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for flag-waving that I've seen is " Populist expression of patriotism".)