Cry, but pay up (3)
I believe the answer is:
yap
'cry' is the definition.
(thesaurus)
'pay up' is the wordplay.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'pay' in reverse letter order is 'YAP'.
'but' is the link.
(Other definitions for yap that I've seen before include "Yelp" , "High-pitched bark" , "Small dog's sound" , "Pay up for chatter" , "gossip -" .)