One paid to attend clean form of entertainment? Maybe not (3,5)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

I think this must be: an envelope (‘to attend’) of A (‘one’) plus PD (‘paid’) in LANCE (‘clean’ – to pierce an abscess). ‘Maybe not’ completes an extended definition. As pointed out first by Dr. WhatsOn @3, LANCE is an anagram (‘form’) of ‘clean’.