A group heard to accumulate (6)
I believe the answer is:
accrue
'to accumulate' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for accrue that I've seen before include "(Of money) be received in increasing amounts" , "Grow by addition" , "Accumulate or amass like interest" , "Grow like interest on capital" , "Increase by periodic additions" .)