Young man with charisma rising and rising, then falling (5)
I believe the answer is:
tidal
'rising then falling' is the definition.
(the tide rises and falls)
'young man with charisma rising' is the wordplay.
'young man' becomes 'lad' (I've seen this before).
'with' means one lot of letters go next to another.
'charisma' becomes 'it' ('it' can mean a special quality or charisma).
'rising' says the letters should be written backwards (going up in a down clue).
'lad'+'it'='ladit'
'ladit' in reverse letter order is 'TIDAL'.
'and' is the link.
(Other definitions for tidal that I've seen before include "(Waters) subject to moon/sun" , "Concerning lunar-driven ocean movements" , "Like the sea" , "(Of the sea) ebbing and flowing" , "subject to regular surges" .)