Charlie and I see her sadly becoming more tacky (8)

'more tacky' is the definition.
(cheesy can mean tacky or of bad quality)

'charlie and i see her sadly' is the wordplay.
'charlie' becomes 'c' (phonetic alphabet: alpha, bravo, charlie etc.).
'and' is a charade indicator (letters next to each other).
'sadly' indicates anagramming the letters.
'i'+'see'+'her'='iseeher'
'iseeher' with letters rearranged gives 'heesier'.
'c'+'heesier'='CHEESIER'

'becoming' acts as a link.