Fall in lumps? (5)
I believe the answer is:
slump
'fall in' is the definition.
(slumping is a kind of falling in)
'lumps?' is the wordplay.
'lumps' can be anagrammed to 'SLUMP'.
However, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for slump that I've seen before include "Heavy fall" , "Bad economic recession" , "flop" , "Deep recession" , "Economic depression" .)