Rugby-playing group quietly steal apples (6)
I believe the answer is:
scrump
'steal apples' is the definition.
(I've seen this before)
'rugby-playing group quietly' is the wordplay.
'rugby-playing group' becomes 'scrum'.
'quietly' becomes 'p' (p for piano and quiet).
'scrum'+'p'='SCRUMP'
(Other definitions for scrump that I've seen before include "theft" , "steal from farmer" , "Nick in garden" , "Steal apples from trees" , "Nick apples" .)