Festivities attended by German leader, unfortunately (5)
I believe the answer is:
galas
'festivities' is the definition.
(I know this)
'by german leader unfortunately' is the wordplay.
'by' means one lot of letters go next to another.
'leader' suggests taking the first letters.
'unfortunately' becomes 'alas' ('alas' is used to express regret).
The first letter of 'german' is 'g'.
'g' put next to 'alas' is 'GALAS'.
'attended' acts as a link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Another definition for galas that I've seen is " Bashes".)