Enter unwelcome fall of receipts (9)
I believe the answer is:
gatecrash
'enter' is the definition.
(gatecrashing is a kind of entering)
'unwelcome fall of receipts' is the wordplay.
I cannot quite see how this works, but
'fall' could be 'crash' (crashing is a kind of falling) and 'crash' is located in the answer.
'receipts' could be 'gate' (gate is a kind of receipts) and 'gate' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for gatecrash that I've seen before include "Try to get in for free" , "join party if not wanted" , "enter without invitation" , "join party unofficially" , "to do so uninvited" .)