Drunken rugby player, mostly stylishly dressed (7)
I believe the answer is:
bacchic
'drunken' is the definition.
(synonyms)
'rugby player mostly stylishly dressed' is the wordplay.
'rugby player' becomes 'back' (type of rugby player).
'mostly' means to remove the last letter (most but not all of the word).
'stylishly dressed' becomes 'chic' (I can't justify this - if you can you should give a lot more credence to this answer).
'back' with its last letter taken away is 'bac'.
'bac'+'chic'='BACCHIC'
Can you help me to learn more?
(Other definitions for bacchic that I've seen before include "Relating to the god of wine - riotously drunk" , "Like the Greek god of wine" , "Jovial" , "Relating to the Greek god of wine" .)